I'm so glad someone finally brought up safety. For a long time, I have been livid with how easily so many people just go along with the desire to avoid liability and litigation, even when it results in the exact opposite of safety. I've repeatedly been the unpopular one where I teach because of this, especially because there's the double-whammy of these kinds of decisions also being made about kids who by and large have rather overbearing parents with a lot of time and money on their hands. Sorry, I'm not supervising a high school junior with a driver's license who can do graduate level math to walk 100 feet to a vending machine.