I had the same thought, lol! Americans don't kiss as a greeting. I'm pretty sure the French do, in addition to some other European cultures, but they would never casually kiss someone on the mouth. They do really simple pecks on cheeks that barely touch. And it's only on the cheek...never on the mouth. That'd be way out of line for almost everyone worldwide.
Yeah, I think it's not uncommon for family members to kiss each other on the cheek. In my family, it's usually the older generation kissing the younger generation on the cheek. But it's not common at all between young family members. And it does NOT happen between friends or acquaintances. It's pretty normal, though, for little kids to mix it all up and not know when affection is appropriate and when it's not. But that has nothing to do with American culture, lol!
why do japanese people think that americans kiss each other all the time? If you tried to kiss someone you weren't dating as a "greeting" you'd probably get smacked ┗( T﹏T )┛