“I can’t really get on board with imprisoning them unless they’ve broken some law, and I think just making homelessness illegal is pretty heartless.”
I think leaving them homeless is pretty heartless. Making Homelessness illegal is not heartless: It means being determined to solve the problems that lead to homelessness. Making it illegal is taking the strongest possible stand against homelessness, and refusing to accept homelessness as an ongoing condition. Until fairly recently vagrancy was against the law, and vagrancy is just a fancy word for homelessness. Whether it is a prison, a mental home or a homeless shelter they end up in, the critical thing is that society refuse to accept homelessness as normal, and takes whatever action is required to care for them. That might include imprisoning them until they are well enough to look after themselves. It will at least provide them with a warm bed and three meals a day.
After Homelessness becomes a thing of the past, I plan to make poverty illegal for all citizens, and wipe that shameful condition out as well.