I work down in Mexico just about every week and I second the comment about corruption for tourists hasn’t been a problem in a while. The biggest issue down there is getting caught up in the turf wars going on along the border. If they’re offering a van that can safely get you where you need to go then you should be fine, but anytime you’re traveling in another country you need to be careful.
With that being said, I’m signing off now for my trip to Cozumel. We depart from Houston at 9:30 this morning!