Europe as a whole is much older than the US, which means its city planning, population density, and having places to put cars for everyone is just different than the US. Here, cities were waaaay smaller when cars first came out, they could be planned around cars, and we had the room for suburban sprawl (which means less density, which means mass transit can't be so, well, massive).

So not to be defeatist, but even if we put significantly more funding into mass transit, it would still be choked up by our city planning, which is going to be way harder to overcome. Thus, we need cars which means we need cheap fuel for it. I'm fortunate enough to have an EV and work from home, but other households can be spending hundreds of dollars more per month (or more) on gas with no practical way out.