Beats me. They should probably start with permanent contracts from the outset and work upwards from there.
Edited to add, in the balance of fairness...there are worse deals out there, although even those are few and far between. Not exactly a lot of cadet deals full stop! Still, can fully understand the "race to the bottom" sentiments. I've watched my previous sector (cultural heritage) do precisely the same thing with the increasingly huge prevalence of zero hour contracts and complete degradation of T&Cs. It's worse there than in any other area I've come across.