2) IRL it's very complex to value sprawling cul de sacs of suburban development. When first built they're great because the people who live there are the kind of people who almost never need the government, and have a fairly good income. If they weren't both they wouldn't be able to afford to buy into a suburb. This means a miniscule tax rate is enough to run the city. Then life happens, and 50 years later you've got houses designed to standards nobody wants, owned by people who were too poor to move out, which means that a) they need lots of government services, and b) they can't pay for those services with the miniscule tax rate, leading to c) the City Manager scrambling around to save the city while the long-time residents are convinced that it's still an upper-income enclave. Quite a few very smart people have pointed out that it's much easier to build new suburbs then build a new Brooklyn because of the way the Feds give out grants.
You missed out on (arguably) the most important factor, which is that suburban sprawl is a gigantic pyramid scheme.
When a developer builds a new subdivision, he not only pays to construct the infrastructure for it, but also spends a bunch of money on building permits and (theoretically) impact fees, which go into the city's coffers. (I say "theoretically" because some particularly short-sighted, pro-development cities might undercharge on the impact fees.)
Those fees are supposed to go towards maintaining and upgrading the rest of the city's infrastructure to pay for the development's impact, but they don't. Instead they get used to balance the budget this year. In a couple of decades when that subdivision's infrastructure needs to be repaired or replaced, where does the money come from? If the city is lucky, it comes from the impact fees of whatever new neighborhood is being built then. If not, then the city is screwed.
The growth of the suburbs really exploded around WWII, so we're just now really starting to see the consequences of Ponzi development. If you think older, inner-ring suburbs are in a bad state now (except for the ones that managed to gentrify, and have all those mid-century ranches torn out and replaced with McMansions), just wait. It'll get worse before it gets better.