I don’t know if there are any regulations or by-laws but there is common sense. Do you also pay their electricity and water bills?
If there is no by-law on your books saying that all owners will pay the costs of commercial enterprises, then you shouldn’t be paying these charges.
If there is a by-law – maybe sneaked on by the developer to make the sale of the premises more attractive – you should rescind it (by a 75 % vote at a general meeting) or go to NCAT to have it struck down.
On what grounds? That it’s a rort, plain and simple.
In fact, you should tell the strata manager to stop paying the bills and hit the commercial tenants or their landlords with backdated bills for previous payments. You can always step away from that as a bargaining tool.
And if the commercial tenants want the owners corp to continue paying the bills, let them take you to NCAT and see how they do there.