It's much the same down under.
Eurasian people have been exposed to alcohol for at least 3,000 years, possibly several times that. Genetic vulnerabilities to alcohol and alcoholism have been deselected to some degree. Native Americans and Aboriginal Australians have only been exposed to alcohol for a few hundred years; they are more prone to alcoholism biologically.
But the main reason, I think, is the social conditions they grow up in. Much the same here as described by SamIam in the OP. Unemployment, low education, bad health, crime and prison etc etc. Hell, when your role models are drinkers, how could you avoid it?
Until 1967 it was illegal to supply alcohol to an Aboriginal person. Well, until 1967, Aboriginal people were officially not citizens, couldn't vote et cetera, due to certain provisions in our constitution. In '67 that was all thrown out, and it became illegal to discriminate against Aboriginal people. Which is a general improvement, but it meant open season on alcohol. Bad.
Now, many Aboriginal communites have declared themselves "dry" and there are laws that enforce this. People were making easy money smuggling booze into dry communities, but this is being policed.
This only works for remote communities where (a) there is no other source of alcohol nearby and (b) the community decides to go dry.
In wet communities, regular towns, and cities, there is no way to legally prevent Aboriginal people from drinking if they choose to, outside of the regular drunk-in-public laws.
If you guys do find a solution, please share.