The problem is not using drugs. The problem is committing crimes while using drugs. Some people can use drugs and avoid crime. Others use drugs and commit crime.
Therefore, you arrest criminals, and offer them jail or treatment that they must follow or they go straight to jail.
Camping on a city sidewalk should be a crime. This is a public space used by everyone, not just one person to make a random house on. Children use sidewalks which are a public good. If someone uses drugs and camps on the sidewalk, they should be arrested and offerred jail or treatment.
Therefore, you arrest criminals, and offer them jail or treatment that they must follow or they go straight to jail.
Camping on a city sidewalk should be a crime. This is a public space used by everyone, not just one person to make a random house on. Children use sidewalks which are a public good. If someone uses drugs and camps on the sidewalk, they should be arrested and offerred jail or treatment.