What I don't understand is why people assume congestion is intentional throttling by ISPs for them to profit later with imagined fast lanes.
Assume? The ISPs have been fighting (a losing battle) for a legal structure that will allow them to do it.
Hell, they're even telling us that is exactly their plan.
In Atlanta, for example, Comcast provided hourly median download speeds over a CDN called GTT of 21.4 megabits per second at 7pm throughout the month of May. AT&T provided speeds over the same network of â... of a megabit per second. When a network sends more than twice the traffic it receives, that network is required by AT&T to pay for the privilege. When quizzed about slow speeds on GTT, AT&T told Ars Technica earlier this year that it wouldnâ(TM)t upgrade capacity to a CDN that saw that much outgoing traffic until it saw some money from that network (as distinct from the money it sees from consumers).