While true, it's not the entire explanation. Apathy is far more of a factor here than corruption; average citizens don't care enough about their Internet access choices to lobby their politicians about it. The incumbent providers do a pretty good job of offering just enough service to keep average people satisfied at a price that is not quite high enough to make customers really angry.

In general, democracies have corruption problems, the US doesn't seem any worse than the median.

I would go even farther and assert that the US is much less corrupt than the vast majority of democracies in the world.

I'd agree with you, I'd go further to say that there are very very few less corrupt than us either.