Well. We're going for something of a carrot-and-stick approach: penalties for those who sneak off without training and supplies. Of course, we won't be able to catch everyone, so it's more a threat than an inevitability, but...

People have an itch to go out and explore. All the warnings in the world won't stop them; that's becoming clear. But only the truly stupid among them are going to decide that even though they could potentially end up in detainment for it, and even though their probability of survival drops exponentially without supplies and someone to watch their back, they're going to go out alone regardless.