rent-out-your-apartment* litigation. Afaik the only case where people have issues with AirBNB is in buildings with shared entrances/hallways.
Here in Australia city and state hospitality organisations are very vocal in opposition to airbnb. The usual argument is why should they be paying to meet licensing/safety requirements when airbnb hosts can rent out their home without regulation. I'd guess 90%+ of these premises are standalone homes.
In my city the local council just announced plans to limit a property to 42 nights of airbnb per year, or face significant fines. Not sure it'll stick.