My HR department says the best way to avoid time-wasters is to carry out a proper recruitment with recruters who can tell a time-waster from a real C/A wannabee. And maybe recruit some of the C/A already in the profession who have lost their job after 9/11. That should bring down the numbers.
Let's not talk about the hornet's nest Ryanair, it's an entirely different matter and would bring us out of our topic.