The AirBnB is already "taxed" when it's empty because the owner still has to pay rates, loan interest, body corp, etc. so they are already losing money if nobody is there. They would appear to be popular enough that that 'tax' is still a better deal than putting the place up for long term rent.

With the recent rule changes limiting rent increases but interest rates still so high, a short term rental is now probably more attractive to a property owner than a long term rental as far as covering the costs of owning the property.

If you want fewer AirBnBs and more rentals available, make it more attractive for property owners to provide long term rents, don't put them all off like they are doing now by making it such a hassle to make a place available for rent.