It’s more complex than that.
The way the US is spread out makes public transit prohibitively expensive and difficult to achieve proper coverage. To make it effective, you would have to shift the entire way we live. Our entire society is built off the concept that everyone has a car.
Add to the fact that building transit is extra expensive in the US and you arrive at the reality that we will NEVER have a working transit system. That’s why the shift to small cars is needed. We don’t have any more room for roads, so we need more cars to fit in the roads we have
We just lack the leadership needed to implement massive programs like high speed interstate rail.
In fairness the Interstate system was more about air defense than transit.