The problem with P2F schemes is that the paying pilot is regarded as a client.
A training Captain does not have the option to send a trainee home even if he is incompetent and 10 instructors have already written him down,
Hence the fact that there is no proper filtering.
Well this depends on the professionality of instructors and company. When I was on training in Air Baltic I've heard that some guys failed the line check and had just a second shot before being sent home....
The fact itself that they do not offer the line training to everybody means something...
I guess it should be the same in other places
, but I don't have information about this