How exactly do you separate politics from sport, when the county/local federation is paying for the preparation and everything? It's not like sports are strictly independable of what happens in the political scene, they are vastly connected, even more so in a country like Russia.
As for the Americans, can't tell for sure but I've heard that CX skiers and biathletes (at least) don't rely on the national federation, but on sponsors and some of them even have to work to pay for their expenses.
I think the latter is the reason why Russian tennis players and cyclists haven't been banned from competition.