It's all semantics really. You could argue that the money get paid back to you over 84 months with a partner airline, but then for that period you are on a reduced salary from other non-cadets to the tune of around the same amount as the 'bond' repayment. The key point is that the debt is in your name and your name alone.
Added to this that the chances of getting 84 months continuous employment from some of the partner airlines have never been so poor, and suddenly it's not quite so attractive. Airlines (orange ones) might like seasonal employees, but banks certainly will not like seasonal repayments!