This sounds less like "mass transit culture" and more like extroversion.

I don't think anybody would call me extroverted. I'm a typical introverted engineer. humans are social creatures!

when you're in a car, the possibility for a positive social interaction is nearly 0. I don't know about you but I've never been happier after driving my car

when you're not in a car, there's just more opportunities for small social interactions. You can choose to take those opportunities or not, but they're there. There's just something different about being eye-to-eye with people and not separated by a sound proof metal and glass cage