On a plane? That's much worse, you can't just change seats or get out if you want to avoid the person. Oh god

Leave me alone.

I once took an overnight flight from the west coast to the east coast. The flight wasn't very crowded and I intentionally picked a seat away from other ocupied seats.

I get on the plane, as I'm warking back to my seat I notice there's entire rows that are empty. So instead of picking a seat in an open row, and this. fucking. guy. picked the window seat closest to my aisle seat, and he talked for most of the flight. In hindsight I should have just sat somewhere else when I first noticed him.

It's not that the trains are so full of drunk homeless people, but that trains are affordable and also conductors aren't going to physically throw out a person that could get violent. Planes you don't really get on without a ticket. An entire class of people are filtered off the plane because of that.

And anyway, said group are a minority, but they're the only ones who randomly talk to strangers most of the time. Everyone else minds their own business in my experience.