Not everyone wants to sign up for an exchange. ATMs have a role to play. And being expensive/high fee is not stealing. If they told you a price and then charged you more than that price, that would be stealing, having a high markup isn't, its charging for convenience.
Its crazy how I have people telling me about exchanges when they don't buy from a exchange and people telling me about atms when they don't buy from atms. The atms are stealing money,not giving up bitcoin after you purchase and not giving you money after you sell. The fact that you have to wait by the machine for a hour and the price is marked up so much is only the underlining problem. If you were stuck on the road and your car was on a flat,you wouldn't think I was robbing you if i charged you 1000 dollars?
Do you have any examples of bitcoin atms not disbursing bitcoin when they should have?
Of course they are going to charge some kind of a markup on the exchange rate, this is what gives them an incentive to offer their service in the first place