I think it's a combination of things. People who are reckless because they don't care if they die but also people like that putting others at risk that do want to live.
There's also a chunk that probably couldn't miss out on their income and had no choice but to put themselves at risk.
It also doesn't help that hugging is a sort of normal way to greet friends and Americans in general have a more physical way of socializing.
Including huddling up in churches holding hands, elaborate handshakes and other such things. I noticed that in the protests too, a lot of physical contact.
In countries like Germany and the Netherlands friends acknowledge each other with a nod or a slap on the shoulder.
Only BFF's, lovers, family etc. hug and even for the latter that is fairly uncommon in public.
It wasn't hard for us to stop doing handshakes as that is the only type of physical contact commonly used when interacting with other people.
I wonder if that's the reason why Germany did so much better than Spain and France at the beginning of the outbreak.