Don't fence me in?

In the course of reading this Slate story on GPS monitoring of criminals, the following passage struck me as almost absurd in its juxtaposition:

One hundred state and local jurisdictions are reportedly using GPS to track nonviolent juvenile offenders. . . . And consider the alternatives. Some kids in the California youth system have been put in cages. People living near a juvenile delinquent "ranch" in Santa Clara County want a fence to keep kids inside. Officials there hope GPS can solve the problem less drastically.

Those cages sound pretty bad. The linked article seems to point to serious abuses within California's juvenile system. But what is so outrageous or drastic about a fence? These are kids who have already been convicted of crimes and they are supposed to stay put so they can be rehabilitated. This is not like building a fence along the Mexican border Pat Buchanan style. Hell, even some of the high schools in Alief had fences around them when I was growing up; the kids weren't allowed off campus, and the schools are in a pretty urban setting. So what is the big deal about putting a fence around criminals? Crikey.