I agree, it is a rather perculiar habit which is also practised (more so I think) in hotels, I had a friend who was the concierge at a famous London hotel and she used to tell me of all sorts of things going missing (think showerheads and irons). In a rather nasty Best Western last summer I also found a price list for all the items in the room- furniture and TV included!

Sometimes things can be stolen for a purpose however, I along with my siblings was taught how to eat 'properly' using cutlery stolen from BA meal trays (back when BA did a full 3 courses in Y in Europe) - being of mini size it was the perfect way to teach a small child how to use real cutlery. We had about ten sets as I recall which are still being recyled around our family!