When you book an Airbnb you can choose the number of guests that will be staying. The maximum Airbnb allows is 16 guests, but it’s up to the guest to set a limit. The most common I’ve seen have been 5-6 guests maximum.
Also, most airbnbs I’ve used have had a ring doorbell, and in one case a security camera pointed at the front door. The ring doorbell will alert them whenever there is motion at the front door, and they’ll be able to see who is coming into the property. There’s also usually clauses in their “terms and conditions” that state if you have more people than was booked well charge you extra blah blah.
Bottom line: if you run an Airbnb you’re going to make massive amounts of money and can essentially do whatever you want with it.