Sine the airport doesn't directly employ most of these people, I would think it far more likely that penny pinching businesses are delaying recruiting / training for as long as possible to save a few pounds on salaries. I suppose you could also then pass some of the blame onward to airlines some of which seem to believe that they shouldn't have to pay for any services, and when they do they drive prices down to virtually unsustainable levels.
Airports, handling companies and airlines have been employing temporary staff to cover the summer season for at least the last thirty years since I was one!
Shouldn't really be a surprise to the Id card people, or maybe they're the sort who have done all their Christmas shopping already....