1. The War on Drugs still exists, creating an expensive black market for addicts where they have to commit crimes to feed their addiction - money that goes to gangs/cartels. Researching treatments is difficult due to drug scheduling. Treatment options are limited (like "free drugs").
2. When a particular locality attempts to address these issues in a callous way (like busing), it "solves" the problem for locals, but of course the people still exist and just move to the next town that is not cutthroat. This leaves a disproportionate amount of the problem to those living in cities, where the most services/shelter options are available.
To truly solve the problem, we need to end the War on Drugs, build housing, and properly fund treatment centers on a national level.
Your first option is about as good as it can get when trying to solve this problem using local tools. Safe injection sites, methadone/similar, and housing are all far cheaper than just a subset of what the chronically/drug-addicted homeless cost already and they actually attempt to address the issues of addiction and homelessness. Without housing, drugs/treatment, and injection sites you get: people on the street buying from the black market spreading disease that have numerous emergency room visits and nights in jail, costing everyone far more money than the housing/treatment. But folks in cities will still be paying far more than their fair share to do so and they'll be treating a lot of outsiders from places that don't offer those services, but should - the causes of the problems will still exist elsewhere.