About a dozen round trips and have never had that happen. The openings have vent covers that slant down. Any dust, will settle down past them and not into the carriers. The inside of our vehicles have always been fine. And, as others have said, they do it so vehicles don't get keys locked in (there's always vehicles onboard that use keys). It's policy and I doubt it will change anytime soon.Hi. I saw a post that said they keep the windows down in your vehicle when it is on the train. Why would they do that? Wouldn't the inside of the car get a lot of dirt and dust from the trip since the train cars have openings in the side? Thanks.