Ah - I was unaware of the Australian law change.
Interesting example with the alcohol though. We're not talking about banning anything here - the example might be better described as a particular shopkeeper choosing to only sell alcohol to patrons over the age of 21.
Even more interesting is the "intended use" aspect in the case of alcohol. There have been recent examples of it being perfectly legal to refuse the sale of alcohol to people over the age of 18 on the basis that they may share it with underage companions. (Even though it is legal for parents/guardians to do exactly that).