I wouldn't say it's lack of political will. It's more that we are so excessively bureaucratized and regulated that it just takes more political will to get the same thing done because it will be stuck for years getting regulatory approval.
When there's a will to get it done, it gets done. When her isn't, planning and permitting takes a butt load long time.
If you want good transit, it must be for the people who vote. Otherwise they will vote to make it bad to save tax money. Branding public transit as the affordable option is a guaranteed recipe for failure.
Transit projects must also be small enough that the entity responsible for them always has several projects running in parallel. Once you stop building, you will quickly lose expertise, and subsequent projects will be more difficult and more expensive.