Spending time in parts of Latin America or western Europe or east Asia and then coming back to the US, you can see a lot of ways in which we've built loneliness into the fabric of US culture.
It goes beyond car culture. It's probably illegal to build a cafe within walking distance of your neighborhood or into the first floor of your apartment complex.
Americans get an idea of how bad we have it when we go on vacation, but we don't see it as something that can be built at home.
> or into the first floor of your apartment complex.
I wouldn't trust a cafe built into an apartment complex. I'd expect it to be low-quality, over-priced food placed specifically to try and make a quick buck off people who don't know any better or who physically can't get somewhere better.
You're right that it goes beyond car culture (and zoning laws are part of car culture), but I think it also goes beyond zoning laws. A lack of a social contract between people (individually) and businesses these days is probably involved, too. All these things are interrelated.
As someone who was a libertarian as a child, I assure you the idea of relaxing regulations is quite unpopular.
Lots of factors cause this. Obviously established businesses hate competition. There seems to be a tendency for politicians to make more laws as a bandaid rather than remove old(but this isnt universally true). And finally and probably most importantly, people like the status quo. Change is scary.
Also I live in the suburbs and we have a coffee shop within 2 minutes walking. I just have a hard time paying $4 for a coffee to meet people when most people are on their laptops anyway.
My friends come from sports clubs, parties, and the parents of my kids via birthday parties.