They do it, because we let them do it. They obviously can get away with it.

In fairness, how would people even react? Almost all major TV platforms have ads and all of this is on products long after sale. If everyone is guilty, how does anyone get punished?

Well we aren't just consumers, we are also citizens. Forcing ads into your devices sounds like a collective action waiting to happen, especially if it's done via an update. And further down the road some sort of advocacy group/lobbying may be in order.