In my view, this depends on the laws in the locality where you are renting out/hosting. In the UK there are specific provisions which protect a tenancy, but in no way does an airbnb reservation reflect a tenancy. In fact, in the UK there is nothing in law to prevent a host from entering any place that a guest has access to. For a guest to pretend otherwise, is not to understand or know the law of the UK. Furthermore, if the host/landlord actually gives up the right of access somehow, then he/she is in danger of handing a tenancy to the guest/tenant/lodger.
So how is the guest protected. As far as I am aware, ONLY by means of promises from the host (if these are made) and also by means of the guest's right to leave and review the host. That is it!
I cannot comment extensively on Australia/Canada/USA. Check the local laws.
But as an analogy, reflect on what would be considered standard or normal behaviour in a hotel or a bed & breakfast establishment, in your locality.
re the original complaint. I would have recommended taking photos of the property and submitting to airbnb, along with immediately cancelling the reservation (taking the strict cancellation penalty on the nose, potentially) and putting the dispute into arbitration. This would have allowed the host to rebook and given you the most chance of a full / partial refund. In any event, if the photos diverged dramatically to what was presented on the first day, you would be able to get a refund, no matter what your first contact at airbnb said. Above all, next time, "put it in writing" should be your watchword. I admit I found it slightly ambiguous what you were saying about "essentials" being a pillow.
Of course, an airbnb host might rent out a space on the cheap, without beds, and if the listing did not reflect any beds, then you may have had an argument debating whether the photos reflected the actual listing variables.
If you had the booking and were not refunded, in the UK, your host would not be entitled to throw away anything without giving you notice, and would be potentially subject to an accusation/complaint of theft at the nearest police station.
Hope that helps.