Some people believe mentally ill homeless drug addicts are the tragic, powerless victims of a society which has made housing and medical care unaffordable and deprived them of political representation; that putting a homeless person in jail guaranteeing them food and a bed for a week is unlikely to be much of a deterrent; and that the things that would be an effective deterrent are inhumane.
Personally I don't agree, but I can see why a person would think that way.