In a way, that's fine. You don't need to prosecute all offenders for a law to be useful. The law gives you some way to shut down bad operators which otherwise would be difficult to stop. Compare tax law. By law, anyone profiting from illegal activity has to report it as income on their taxes. This isn't because they actually expect anyone to report it, it's because it gives another avenue for prosecution.

It's worth noting that this distinction between who technically isn't complying and who will actually get prosecuted is a big part of why people have such different feelings about GDPR. Some people are focusing on the difficulty of complying and the penalties that could be assessed; others are focusing on the unlikelihood of small, mostly-compliant, well-meaning operations being targeted.

Also worth noting, this kind of selective enforcement can absolutely be used in a harmful way or have unintended negative consequences. I'm just trying to point out why a jurisdiction might pass a law even if they don't expect anyone to abide by it.

In re enforcement, https://twitter.com/patio11/status/1005093595005665285

"I have mixed feelings about the Japanese Airbnb news. On the one hand: does it seem like the optimal regulation? Probably not. On the other hand: my condo’s live-in supervisor had to update their “We will call police if we spot illegal tenants” policy with “Note: Patrick isn’t”"

(patio11 is that rare thing, a Western permanent resident of Japan, and has lots of tweets on the subject of how Japan combines legendary, genuine politeness with a system that excludes non-Japanese)

IIRC it is enforced AirBnB side, so you can't rent too many days through them without providing the documentation needed to gain an exception.

But this doesn't stop you using other services. While non have the same inertia and awareness amongst the public as AirBnB there are several so it is easy to get around the limit by using several providers who don't talk to each other.

AFAIK the limit is on AirBnB's site directly. Your account is limited until you provide documents from the council. I don't know to what extent people are forging these documents though.

Yes. Indeed there appear to be Airbnb-management companies that help you to ignore it, by inventing fake "host" personas to list your property under and changing it to a different host every now and again. Airbnb themselves don't seem to care if you do this so long as it doesn't look as if it's their responsibility.

(We have been having problems with a neighbouring flat that is being run in this way. The details are murky but it appears to be intentionally managed like this)

Based upon my neighbours; yes completely. Anecdata is anecdata however...

I guess a size-able fine to both AirBnb and the apartment renters with repeat offences to be considered as criminal may help.

serial killers just ignore the fact that murder is illegal, but there aren't too many serial killers.