It's an interesting point but have you noticed that .com is no longer an indicator of a US country? A lot of UK based companies use .com as their primary domain and *if* they use .co.uk it simply redirects.
According to a Director of a uk based ".com" company I spoke to recently this is because the prevailing opinion is a ".com" address has more "weight" i.e. gives the appearance of a more more corporate company. Clearly if I wrote that on Wikipedia it would ask for a citation but it is something I am seeing a lot of. Also individuals used to register .net addresses but I now see people more registering .com addresses regardless of the fact they are an individual and not in the US.
I also just registered a personal domain for someone and they wanted ".co.uk" even though they are not a company because they "didn't like" the ".net" domain and, crucially, a ".co.uk" address is half the price of a ".com" or ".net".