I'll try to be as brief as possible.
What happens, often in airports, is that a lot of the contracts are tendered. It is always the law of the lowest bidder, and it's always the working conditions of the workers who work in service groups, if you want, doing baggage, fuelling aircraft, etc.... There are a number of different jobs. These contracts are always put up for tendering. Companies try to bid as low as possible. There is no obligation for a new employer to respect the collective agreement, wages and benefits, or even to rehire the people who were working for the previous contractor inside that airport, whether that person had been working there 20 years, 10 years, five years or whatever.
Often, what happens is there are no successorship rights, so the union doesn't follow. The new employees are not represented. They lose the majority of their benefits, if not all of them. They are not necessarily rehired, even though they have a number of years of experience. You end up having people who worked for 20 years for one employer doing a certain job. The next day, if they're rehired by the other employer, they could be working at seven dollars, eight dollars or nine dollars less an hour. They could have lost their pension benefits, if they had some, and their insurance benefits, if they had them, or whatever.
That's why successorship rights are so important. They put in a basic wage, at least, that's negotiated inside a contract, and when the contract is flipped to another employer, that employer has the obligation to bid at a reasonable price whereby it's not going to affect the working conditions of the people inside the airports.