The right place to stop the problem for a city/county/state government in a country with freedom of movement is different than the right place to stop for a fed

The right place to stop the problem for a city/county/state government in a country with freedom of movement is different than the right place to stop for a federal government with immigration controls. I.e. SF is never going to be able to fix the problem of people being too poor (or addicted or mentally ill or whatever), due to arbitrage opportunities.