Actually, i'll speak from my view, homeless people generally don't have to what's required to buy a weapon or even a fake one, it would rarely get through their mind to actually rob a bank, they generally just think about getting warmed up and just surviving.
And about the prison, most of them might be conscious about the prison, the inmates aren't generally here for "fun" or make friends, i assume it's a kind of fear, or also a hope that if they keep on being good and unbothering people the karma will hit just right and bring them out of this hard part of their lives.

Ngl it's a question that worth being asked 👍