Just like every other drug problem these people take a prohibitive approach to the problem which is destined from the outset to failure.
As can be seen from the Vegemite issue people are creative by nature and will find a way to satisfy their desires.
One of reasons that alcohol is a problem in these communities is that the people living there largely unemployed and on public assistance. They have huge amounts of unproductive time to fill and alcohol is one way to numb an under used mind.
Cut their public assistance payments to the bare minimum and their underutilized minds will find more productive things to do that drink themselves in to a stupor.
These communities impose the bans themselves. It’s not imposed on them by anybody else.