I don't think the CTC scheme is quite as bad as some of these other schemes for several reasons:
1) CTC cadets don't pay to sit in the RHS to gain experience.
2) An allowance of £1000 as well as duty pay and sector pay are paid to the trainee.
3) They are almost certain to be offered a permanent contract at the end of the 6 months (especially Easyjet), hence companies aren't (in the main) using this as a way to get cheap employees for 6 months before letting them go.
4) The type rating is paid for by the airline, so not only is the trainee not paying for line training, but they get a free type rating.
However, maybe I'm biased as I'm an ex-ctc cadet
