Firstly, I'd say we need to both radically alter our current drug consumption laws in the US, and simply keep and/or increase penalties for crime while on substances. If people want to use, they can either use responsibly or rot in prison. And as a quick aside, I'd Tier prison quality by type of crime/number of crime. At some point, when you're on you're 3rd meth offense, you're simply going to a sh1thole that we simply don't care about the people in there - or, you can chose to be humanely euthanized.
As far as social services, it really needs to be revamped to be far more limited than it is now. Need a place to stay? No problem. You can stay in the community shelter. That means sleeping on a cot with 100 other people around you? Damn, that sucks. Need something to eat? No problem. Go to the grocery store, get the generic bulk ground beef marked for social services consumption, and buy it with your National ID card + unique personal pin. Don't have either of those? Either go hungry, or, hit up the soup kitchen.
Social services should exist to keep you alive so you're able to find work and support yourself, not so you can live like normal people. That is entirely the problem: We keep deluding people that they are normal while collecting social services - they are not. Stop the delusion.
Chuck