As an example, here is one of the federal prison camps where computer hackers have been sentenced. Taft Correctional Institution

There are no fences around the camp, but it is in the desert and there are security cameras.

Photos and article here:

Taft Correctional Institution Satellite Camp in California

quote from article:
"...When not receiving visitors in the main building, inmates either sit around in the shade, many chain smoking to kill time, or walking aimlessly around the grassy portion of the yard.

During the summer when temperatures often exceed 110 in the shade and humidity is overwhelming because of irrigation from nearby farms, many prisoners retreat to their air conditioned dorms to spend the hottest portion of the day reading, napping, or watching TV. Otherwise, there's a small library.

Some inmates are allowed to volunteer to outside agencies and organizations in the community. The inmates are not paid for this outside work, its done strictly on a voluntary basis. These inmates are escorted by staff or specially trained people from the community when outside the facility. As a part of this program, Camp inmates assisted in the building of three homes for Habitat for Humanity.

Another program involving inmates is Striving Toward A New Direction (STAND). This program brings at-risk youth to the Satellite Camp for inmate presentations about how their choices resulted in their incarceration. ..."