And airline companies have great lobbyists in Congress, much more influential than ATC unions.What do you mean about 'allowing' people to resign? Resigning and fleeing are two different things. In legitimate and responsible businesses they know the impact mass layoffs or voluntary retirements have when strings are attached. eg. do this now and you'll get a severance package or be prepared to get fired without any financial cushion. Disemboweling businesses is what a hostile takeover does.
Respectfully, you throw that word 'qualified' around as if there are throngs of people in the aviation industry who aren't qualified for the job. It takes 5 years for an ATC to be able to do the job solo. Five years. You know what drives the increase in air traffic? It's customer demand. Do you really think the American public will be okay with a drastic reduction in air travel while hundreds of ATC go through the training for their jobs which takes years. Working in a toxic environment where the threat of losing your job is a terrible way to do business and that more than anything else: increased traffic, over stressed airports that struggle to provide services is a sure fire way to see more and more of these tragic events.
Try getting the big airline players to cut out very busy routes. Oh, sure, they'll make a big sacrifice and cut out a flight from Kansas City to Reno, but wait for the howls when they are all asked to cut out flights into KDCA.