Sorry pru but these are unqualified teachers going through a training process, not simply unqualified.
In state schools teachers such as these are watched heavily by their superiors and there is a lot of regulation as to what they are actually permitted to do.
The same cannot be said for private schools.
Plus, state schools do not simply employ these types of teachers long term, they are being trained usually by that school on a short term basis (a year or two maybe). All trainee teachers are supported financially to train in case you were not aware of that.
It is the same as PGCE students, my DH taught while he was studying his PGCE, was given financial support towards it and recieved training on sight at the school, while having restrictions on his role till he was actually qualified and started a contractual position.
Essentially he was an unqualified teacher but because his training route was a PGCE, he was not called an unqualified teacher but rather a PGCE student.
Very different to a private school where the person is not training but employed on the basis of their already existing skills which may lack full training if any. And there is no guarantee of the same kind of regulation as a trainee teacher or 'unqualified teacher' who is being trained to meet strict state imposed standards.
IYSWIM.