I had always known for a long time the "why" I didn't want to go out on weekends and such, but it wasn't until I watched some of those videos from "Not Just Bikes" that it really, really struck me. I literally dread finding parking more than I enjoy finding friends.
And suburban (and frankly disturbingly high percentages of urban) America IME is a strange cross between in constant proximity of others, and constant suspicion of others. Like there's just enough people around to not be alone, but not enough to feel safe for many.
There's another comment in this thread positing that the social closeness of the old days broke down because of more urbanization, but it's clear it's sprawl that's killing socialization.
The other day a friend and I were talking about cities since I complain a lot about this now, and we did a quick check: Houston is far, far LARGER than say, Zurich, but their population density is a fraction. Everyone lives in cars that don't talk to each other, going to little boxes that mostly don't talk to each other. And the parking lots required for people to travel to a restaurant or bar means that there's less restaurants and bars.
Incidentally, I've found a single combination pedestrian/bike trail near me, and it's busier than the other trails, and people there are so much friendlier. It's a joy to go, and I'm slowly realizing I may still be introverted, but being out and about without it being a chore actually alleviates a lot of my anxiety.