There is a lack of funding for enforcement. Where I am, the AirBnB market is huge, has led to unprecedented house price growth, and there were already rules requiring short-stay properties to be licensed...85% of properties on AirBnb aren't licensed, and department is a handful of people that are somehow meant to monitor tens of thousands of properties. I have heard of councils employing people to check but that means: looking at properties online, going to the area, trying to work out where they are, finding out where the property owner is (AirBnb have said they will refuse to comply with any requests from local govt).

The rules have been made more solid now. They are introducing a very punitive fine and some areas can have no short-term rentals but AirBnb has thrived because they exploited regulation. Local govt has to be in control (although where I am, the reason they didn't introduce anything even stricter is because the tourist economy is so large...so...it is tricky when there is money coming in).