Re Since when is Tor popular?
Think back to the mid/late 1990's as the start point for some onion routing topics.
Naval Research Labs Review had the 1997 paper "Private Web Browsing".
Would early/mid 2000 be another interesting time? The funding, grants, press where in place by 2005. More grants over 2007-2010+

Follow the funding back in the day (Office of Naval Research and DARPA), understand the funding for the huge costly, fast exit nodes in the US early on.
The origins where for open source intelligence gathering by the US mil and the US gov support of "freedom fighters" spreading democracy.
The main issue early on was any user of the tech would be seen as a tool of the US gov. Not good if emerging human intelligence stands out on any telco system.
How was this set back to be fixed? By flooding the network with diverse users globally and offering free bandwidth, better speed and pushing the an open source grassroots technology front.
The press, dissidents and whistleblowers, all kinds of sites started to spread news about wanting to help people the in repressive countries.
ie a large group of users had to be created allow gov users to hide and help with the node/relay.
Carefully crafted news dropped the military and intelligence origins and pushed the press, First Amendment, dissidents, protected speech side.
Follow the early grants back ie "Pass-Through" funding.
Terms like '“Basic and Applied Research and Development in Areas Relating to the Navy Command, Control, Communications, Computers, Intelligence, Surveillance, and Reconnaissance.”" seems to be floating around.
Finally we got to Snowden and the Stinks page. "Critical mass" - the users are all on the same network, and we are back to the fast exit relays question.
Follow the few law enforcement stories, if you have all data moving out of a network, around the world a few times and then back into the same network?
Its simple to find the in ip, back from the message sent. We also now know that the "internet" in some countries is a known network Tempora https://en.wikipedia.org/wiki/... and XKeyscore http://daserste.ndr.de/panoram...

Thats a lot of cash to just spend on letters and a database. The letters get tracking and logging started within a legal gov framework. Someone seems to see a long term plan with the letters and logging funding. The chilling effect of just knowing your in a database and all your net use is been reviewed? Interconnected local databases? A digital version of the classic anti-social behaviour order (ASBO) at a 'community-based level?
That could see a vast network of watching, logging, reporting and costly face to face meetings with some 'injunction' that flows to a criminal offence if breached.
A lot of free support from tax payers for a new more very local ACTA :)

A per year quota that uses your details as the only unique information? Your address, isp can change but the count stays with you as the person who signed up with that isp and ip as found.

Yes the 4 letters show a history of infringement and the isp's can show bandwidth use too. Its the legal cover for the hard part of traditional cases for free via a stored database of letters sent.
Some nice political cover and colour of law. They only want to educate you with warnings.
Its the lawyers that take the final step to seek an identity. The gov and providers can walk away from any long term logging questions. Months of stored logs are just for the 4 letter compliance.

AC its just post ww2 branding. When the Soviet military looked around for people it could trust it had to find people who where not killed by ww2 "Fascist" Germany and would want to support East Germany. A bit like the Neocons/Trotskyist in the USA - you work with what you have and shape it over a few generations.
Fascist as a slogan solved all the generational ww2 problems for the emerging East German. Every old person was tainted by it. The next East Germans could be seen as safer as they where shaped by the new gov. In this role of undoing the harm "Fascist" Germany had done to Germany, wider Europe and Soviet Union great care was taken with domestic branding to make young and old understood what the price of rebuilding from rubble was all about - stopping "Fascist" Germany from reforming and going to war again.
The old people just wanted to forget the war and rebuild, the young people on average thought a new nation not at war was a nice change considering what Germany was like.
So to an average outside person looking in, reading books and picking up words you would see the terms "Anti-Fascist" a lot. You would see aid to Africa/Asia as been socialist. You would read about East Germany spending vast sums on support to back "socialist" revolutions, science, sport, space.
Deep down the Stasi knew the truth. The Soviet Union was paying real cash to rebuild East Germany, they where always going to be in debt, a post ww2 political bargaining chip.
The slogans fooled the West, the public, a few AC's on slashdot and provided nation building. The Stasi understood reality they where in - they needed real hard currency, needed to rebuild and needed to project a nation of science, wealth, sport, 3rd world aid, space science, nuclear power... but had no cash, just huge loans and some export deals with huge sneaky Western brands seeking very cheap workers. The Stasi also worked out one vital fact. The Soviet Union would never protect them long term, East Germany was for sale to the West. Price was the only question. So the Stasi worked hard to keep their power knowing their nation was all they had. Anti-Fascist aspect kept Russia happy and Russian support flowing, "socialist" worked well in their part of the world. The rest is just West Germany playing its own games with the US and UK for extra support. The real "Fascist" escaped with Operation Paperclip https://en.wikipedia.org/wiki/..., worked without issue in West Germany or at a low level faced tame courts many years after ww2.
In the East Germany they just replaced the old uniforms, found new songs and added new colors to the mass rallies with new "socialist" books to quote.
There is often a lot more behind terms like "Anti-Fascist Protection Rampart" than just found in "Cold" War history books AC.

Money was not really the issue. A nice home, a good education, travel papers to the West (not been restricted only to the East/Soviet Union) was a real goal worth attempting and protecting.
The problem was even if you put in the hard work, stayed loyal to the gov and its meetings, had the skills you might not be able to escape your parents pasts.
ie same skills, age, level of trust to a point but if your parents where pre ww2 wealthy you might not get anywhere out of the East.
ie if you got to work in the West the gov kept your family back and watched you. Any issues and your lost that paperwork.
As things got more relaxed with visits from the West people could get small gifts in. Very strange that this study got pushed onto Slashdot by an AC :)

AC if you actually saw an East German factory or product you would note the lack of 'automation'. A few areas that needed tech eg computer design and lens work got the top quality hardware support. The rest of East Germany was left to its own 1950's devices. The East German work force was rather dynamic post WW2 as the people who did not escape kept tiny workshops and firms at first. They produced what they has always made for the gov but where left alone as to how. Later the East German gov reached in and closed all the small brands and firms, pulling them together as vast regional efforts (1970's on). All the ability to over or under produce was lost as well as any advancement in the way things where produced. People got jobs, went to work, did them, went to political meetings and then went home. That was it. There was not much "automation" as that would cost real cash, need cash for spare parts and replace workers who needed jobs for life.
East Germany did not have the spare cash to just waste on automation. They would have had to take out huge loans, import the tech, import the skills, keep it running and then export the results to pay the huge loans back in a real currency. The exception was Western brands invited in to use the workers in the East to make products for export and then share the extra profits with East Germany gov. But that kind of spoils the "Communism" propaganda spin AC. A lot of cash was made like that but it shows a nice cash flow interconnect between East and West that does not fit into the Wall and free West propaganda.

The US tried that for a very short time under Nixon https://en.wikipedia.org/wiki/.... A massive movement of staff to secure the border was in place and worked very well.
The flow of drugs, drug money laundering in US banks and illegal labor was at risk. Over time the US returned to a policy that can be seen today.
A free flow of people, goods and the need for expensive financial instruments ensures wonderful regional profit.
The UK was a great example too with its visa "expires" database. The UK forgot how/why to count visa in and visa out (was International Passenger Survey).
The main reason seems to be a super cheap flow of workers and the UK will try and bring back "exit checks" in a year or so :)
As for US policy - cheap workers with no on site wage or health laws was always the big win to keep wide open boarders for decades.