The thing is, in the long run it doesn't matter whether you are legally allowed to install your own switch. The price manufacturers charge for a car will adjust based on whether they can get revenue from subscriptions or not. If they can't successfully charge subscriptions, base car prices will go up.
This could stand in as justification for any odious pricing practice. "Sure, they sneak cocktails onto their customers's bills, but if they didn't do that, they would have just charged them more for their dinner, so it doesn't matter."
The thing is, base car prices go up anyway, and subscriptions are an additional revenue stream. If manufacturers can get away with charging for anything, they will surely charge for it.
