I appreciate what you're saying but number of public websites with different language options which weren't meant for countries outside of the US is going to be pretty low relative to the alternative. Occam's Razor would suggest those sites are generally intended for international consumption.

However, to get back to my original point, I was commenting about how all countries nationalise common language; and regardless of the justification of using an American flag for English language options, it's still an example of that point.