I have had official confirmation that the listing facility described as 'free parking on premises' means "as long as there is free parking available in the area that is all we require of our hosts [airbnb]." 'On premises' means 'private' and therefore airbnb is actually encouraging hosts to use inaccurate and legally false information. Why name a dog 'a cat' if all that you require is that it be a pet - in other words why not use 'free parking in the area' instead of 'free parking on premises' to mean free parking in the area?
It seems to me so obvious that whoever first came up with the term intended it to refer to private parking that it beggars belief that airbnb would try to argue otherwise. Not only does it open up the whole parking situation to abuse (who doesn't live somewhere where there is free parking somewhere in the 'area' however it is defined? is it still 'free parking' if it is not free 24/h or if there is never a space) but it also deprives hosts with private parking of making this clear in the pre-chosen tick boxes. Of course details can be provided in the listing but the whole point of the tick-boxes is that they can be used to filter unsuitable properties.
So I would assume that this is another instance of poor customer service rather than a deliberate attempt to undermine the transparancy and honesty of the system. I hope someone with more experience of airbnb can take this up and have it resolved so we can continue to have confidence in the system.