Obviously it doesn't strike you as odd as an American.
I'd say, .com is just the default. If you go location/topic specific, you go with another TLD.
To the 130 million (domainnamestat.com) domains, registered in the US, there are like 500 million domains, registered somewhere else. I couldn't find any numbers for how many of those are .com and how many aren't, but you cannot just ignore those. Just because most domains registered in the US are .com domains, doesn't make .com a US domain. That's a really egocentric point of view.