> (i.e. loud and busy environments with many strangers, often physically closer than comfortable) is unnatural to begin with.

What is unnatural about this? We have plenty of anthropological evidence that humans have been doing massive festivals for at least many thousands of years i.e. people voluntarily gathering together with strangers in loud and busy environments with all sorts of sounds and smells.

We still have festival type experiences: concerts, street festivals, gatherings in a park, church, etc. None of them particularly look like the bus.

Ah yes, that natural many-thousand-year-old massive festival tradition we all know and love: the twice-daily subway ride. Good comparison.