Traditionally, strata managers have avoided putting maintenance funds into interest-earning accounts because that would attract tax which would cost more to calculate and submit than you’d earned.
Strata managers are required by law to have separate accounts for each Owners Corpration but that doesn’t mean separate bank accounts – just a record of the amounts that they hold in trust for each owners corp, and for what purposes.
If you are self-managed then you probably need to ask whether the minimal interest you might earn in a commercial account would be more than offset by tax and acounting implications.