Revealing mistake: Just after they dump the tacks out of the window, the Russians' car flies up into the air in a really quite impressive car crash. Just before it flips over though, you can see the huge ramp put in front of it. (00:32:20)
Revealing mistake: In the big impressive car crash, it is quite clear that most of the cars are empty.
Revealing mistake: In the scene at the tent revival, as Cab is ascending through the tent ceiling, a clear plastic sheet can easily be seen.
Answer: He was just saying it pessimistically. Although, depending on which reports you read, 1 in 3 children are abused by their foster parents. In addition, many children in the system also get placed into several different homes during their childhood (since fostering children is not the same as adopting them), leaving the children to feel unloved by their foster parents.
I don't know the frequency with which it actually happens, but there are also neglectful foster parents whose sole motivation is the monthly stipend from the state, rather than a genuine interest in their wards' well-being.