It also sounds like they are sold on the empty promise that these jobs will get your foot through the door into the lucrative technology industry.
See abusive relationships or this handy article http://www.issendai.com/psychology/sick-systems.html
Due to the low physicality of the work, there are likely people who consider it easy work, despite the psychological impact that seems obvious to you or me.
I don't expect these contractors to get much long term benefit from the position. And it sounds like most quit or get fired.