I always felt every big city should have a certain area cordoned off with a high wall where anything goes. Drugs, gambling, prostitution. A guarded entrance at one end and a morgue at the exit. Maybe even a Thunderdome for gang shootings.
Keeps the riff-raff off the main streets away from decent people.
I think that’s really the solution. No prisons for offenders, just send them to “Pleasure Island” where they have to live and have as much fun as humanly possible, until they die.