From my times working in other countries, I've met plenty who were surprised by the general friendliness of Americans and our prevalence to greet people for no particular reason.

I will agree that over the past year the people on the MUP have been a lot less friendly, but I've attributed that to the greater number of random users and the wariness of catching something deadly from random strangers. As the pandemic is showing signs of winding down and the solution is becoming more wide spread the wariness is subsiding and the friendliness is reemerging.