Let me ask you this, if you neighbor decides to keep a bunch of poo in his back yard and you can smell it 24/7, are you going to complain or just live with it since he is free to do whatever he wants at his own house? (assuming no legal issues with it)
That is probably not the best example but you get the idea. Yes everyone is free to make their choices, but if the consequences impose problems on others then depending on the nature of it, they might be liable.
And in like vein, let me ask you this. If Colorado allows cars to have 5% tint but Oklahoma only allows cars with 2% tint, and a car drives from Colorado to Oklahoma, is that car causing problems for Oklahoma? It is a violation of Oklahoma law certainly, but the Oklahoma legal system can assess fines to cover the cost of enforcing Oklahoma laws within the Oklahoma state line.