I'm with Ivor on this one. I don't think bonding works. Where I've seen it tried it has been ineffective - it will often cost the employer more to recover what might be due and tends to attract unflattering publicity, particularly when it's a big company and a young trainee.
One would hope that the recruitment process would weed out anyone with captainjohno's motivation. Nonetheless, if someone gets through their training then good for them - if they happen to want to go elsewhere or do other things, good for them too. After all, you only live once, and some might say that to have trained as a controller at 18 and done the job until retirement was a waste of many other opportunities. To each their own.