I think you forgot Tokyo.
Anyway, interesting stuff.
>> What can we learn in order to catch up and start once again properly expanding our transit systems?
Basically in the US we have a perfect storm of political, fiscal, regulatory, labor, and planning hurdles that make it unnecessarily hard & expensive to deliver mega projects, and transit in particular, compared to other highly developed countries. There is no single answer, and it is definitely not an issue of US labor simply being more expensive (although that is part of the answer). The most serious work to date on this comes from
Alon Levy's Transit Costs Project, which everyone interested in US transit should at least be aware of.