@Lorna3 to me, the problem lies in what Airbnb classifies as an "infant". No parent refers to their 2 year old, or even a one year old as an infant, unless they're trying to get away with not paying for them.
True infants, i.e. babes in arms, not yet mobile on their own, don't cause damage and don't make a mess. A mobile one and half-2 year old can definitely cause a lot of destruction and a huge amount of mess.
If Airbnb changed their age descriptions to Infants, 0-9 months, Toddlers, 10months-2 years, and only allowed true infants to be allowed to stay for free, that would solve a lot of this BS. It's pretty hard to pass a 2 and a half year old off as a 9 month old.