I think it's entirely appropriate as well. The concessions are being given a very prime position with inherently limited competition, so it's not really a free market; it's an oligopoly at best and, in some lines of business, a monopoly.

Way too often what happens is that the concessionaires will take advantage of this with higher prices, and then the airports will do the WRONG thing and raise rents or other charges to take a cut of that money. The government should be looking after the passenger as well, rather than treating it as an exercise in how much money they can try to get out of the passenger.