They catch kids easier in a rural area than an urban area because they can lock the area down.
Take Bonners Ferry, Idaho, where Boulder Creek Academy and Rocky Mountain Academy are located. Two campuses, about 15 miles from the nearest town of 5,000 people, surrounded by tons of nothing but wilderness. There is one road that will take you up or down the Idaho panhandle, one road that will take you to Montana, and one that will take you straight to Canada. And a railway system.
So when a kid runs, escorts and local authorities pretty much already have the kid caught. Program kids stick out like a sore thumb in a rural town like Bonners Ferry, so they can't hang around there for long. Half the people in town will be on the phone with the Sheriff's dept. as soon as they see the kid, whether they know there's been a run-a-way or not. Trying to jump the train? As soon as a run-a-way is reported, the train is searched as soon as a cop can get anywhere near it. The border? Forget it. And by foot? Not around there. Through the wilderness? Better be prepared...and they'll utilize helicopters as well as some pretty high-tech shit like thermal and night vision apparatus.
Think any of those precautions can do any good in the city? Never. It's so easy to blend into a city...and there are for more resources to utilize in order to reach your ultimate destination; home.
Am I saying a wilderness program is foolproof against escape? Hell no! People who had their escape thought it could make it with ease. But would I rather make a break for the city than the wilderness? You bet your ass!