You're right that this is a very American thing. But we are a huge country responsible for huge amounts of climate damage. Our parking lots are enormous. 5% of our entire country is parking lot, owned by companies that can sure as hell afford contractors, especially if there's incentive.

Also, here, banning cars in city centers here often does NOT work. Even the city I live in tried it for decades - businesses constantly failed, there was no foot traffic despite being surrounded by residential communities and beautiful upkeeping of the town center. Once we opened it up to cars, suddenly it's a flourishing area of local businesses and community organization. We as a nation are too focused on cars, yes. But changing that right now is absolutely not happening. There's no alternative right now, and changing that has too much opposition to overcome. There has to be steps along the way. Covering massive bare parking lots in solar panels would absolutely be something we can get this country on board with.

I don't know of any big cities that have banned cars from anything but small areas in their centres. I know that in my city, the centre of which is pedestrianised, nevertheless has many car parks, including two large park-and-ride facilities with large car parks that could have solar panels installed.

The reason to build them over car parks is because the ones being considered are surface-level, so any building work is cheaper and easier. And it also provides a benefit to users in the form of shade.

Ultimately we should indeed aim to cover rooves with solar panels, but let's focus on the lowest-hanging fruit.