I don't blame the airlines. This is capitalism at work. It is the duty of government and regulators to ensure that passengers are protected. Joe public has no idea if the guy in the LHS has paid his way in. The public assume that the rules are there to keep things safe.
A sucker is born every minute so there will always be a supply of people willing to pay so the airline can exploit this commercial opportunity.
I would not have a problem with the cadet scheme if it were purely to generate pilots and not income. What future can there be for these FO's if the airline is motivated to replace them with a new income source.