"I don't think they are "cages" per se.
From reading the descriptions, it sounds more like homemade cribs, and a jury-rigged set up to alert the parents if the kids go wandering at night (as children, especially autistic children, are want to do)."
Admittedly I don't have children, but I dont think of cribs as having lids or being stackable.
You can buy the lids at JC Penny's, Target, and evern Amazon:
http://www.amazon.com/exec/obidos/tg/detail/-/B000056HLX/002-3564609-5745650?v=glance
The polite term is "crib tent." Sounds to me, being poor (with 13 mouths to feed!), they made their own.