If you are renting out your property, it should be safe for reasonable use. A swing being part of the rental should be safe to use in a normal manner, not to mention that a temporary tenant cannot possibly be expected to know the maintenance history of any fittings.
If I would rent a property through AirBNB (which I won't) I would expect it to be unsafe by default because that to me would seem to be the most prudent way to act. Ditto when I buy a used car, I inspect the thing end-to-end before I trust it, ditto when I buy a new place to live in (the one I just moved into had sub-standard electrical circuitry and I ripped everything out and replaced it with up-to-date and safe materials at considerable expense).
Properties you rent from professional operators you should be able to trust to be up to date, in a country that has a low incidence of corruption.
Anything you rent from private individuals should be considered unsafe by default.
Major rental agencies only. I would never rent a car from a private individual. Nor would I borrow a car from a private individual unless I know they keep their stuff up-to-date.
AirBNB are middlemen, they are not - surprise - in the business of renting out apartments, they are in the business of facilitating the renting out of apartments/houses/whatever and that is exactly where the problem lies. People enter properties they rented through AirBNB not from AirBNB with the same expectations that they would have entering a hotel but with a nicer ambiance. And that expectation is terribly faulty.
