It is true that transit policy is a choice but it is one largely driven by economics. There is also an element of personal preference. Public transit is not pleasant or flexible.
Believing that the US would become eurplope or Asia if not for transportation policy is simply untrue. There are some regions that could adapt but the ones most likely to benefit from and use mass transit already have it and barely use it. The simple truth is our cities and geographies are different.
The tradeoffs you gloss over are likely to be much lore significant. They start with the tremendous investment required to add these where they don't exist and end with the mix of economic and quality or life impacts inherent in this type of travel.
EV do not drop total emissions out of the gate. Most start with a higher carbon footprint (and environmental impact) than ice vehicles and do not break even until more than half way through the expected life cycle. You do get some gains after break even but those benefits are mostly on relocation rather than reduction and are reset when the car hits battery replacement. I like EV's but they aren't the panacea they're presented as and come with their own problems.
The bottom line is that the automobile for all of its flaws represents complete freedom of movement not offered by any other means available to the average citizen. And you want to do away with it.