As more dogs are being taken by their owners to more places (not just airports and airplanes but also into hotels, restaurants in the USA, stores, public parks, special events other than those focused on dogs, etc.), one solution might be to criminalize having an aggressive dog that bites someone, just as it increasingly is a criminal offense to cause an accident because one had been texting while driving. Then there would be punishment even if the dog owner can't afford to pay as well as the deterrent effect.