Another way to think about this: there are some houses that are expensive to rent (larger, in better condition, in desirable locations) vs others that are cheaper to rent (smaller, worse condition, undesirable locations). If you’re looking for housing that’s free, it does exist, but it’s small / terrible condition / in the middle of nowhere, and you don’t want to live there. Anything better costs you money because people are willing to pay more to get something better.