On the first part: because unlicensed hotels are generally unsanitary and unsafe to stay at, are often run by shady operators who may rip you off or rob you, and are a nuisance to neighbors. Also, it's essentially misrepresentation, because AirBnB portrays itself as a place where you rent out someone's room from a real person, but then you're actually renting out a room in a fleabag hotel. If I was looking for low-end hotels I wouldn't be on AirBnB!