The multiple levels of governments and associated regulations is very much preventing it from happening. If any one of them in any of the jurisdictions the train might travel says no (or drags their feet) it doesn't happen.
So what. Y'all managed to raise the minimum drinking age to 21 without passing a constitutional amendment by tying federal highway funding to compliance by the states [1]. There's nothing stopping your federal government from doing just the same extortion again if your politics are too ossified for a constitutional amendment or to get rid of NIMBYs.
So it isn't nothing. It is something. If it were only the states vs the federal government, that would be great! Unfortunately it is also all of the county, city (and other??) local governments as well that have a say. And then in california in particular, things like the environmental protection laws have become weaponized as well to stop.
I suspect it would take something spectacular (like how the interstate system was created) to actually make meaningful progress. And the irony is once it's in place no one could imagine life without it.
