You are technically correct. AirBnB is letting/renting in the broad definition. This broad definition also includes renting a Jackhammer from a trade store, or using one of those pay as you go scooters on the street.

However to use such a broad definition, I am not sure what your original point was.

My point is that there is a big difference between "letting" as what it normally refers to in this context - a lease agreement for people to live in a residential property, with tenants rights implied, and some law covering this area and AirBnB which is more like a hotel service.