I understand your point of view, but it is not exactly as you say.
Of course they take the guys they know from Privat Air and EAT, but the reason why some had to do the whole thing and others just the interview is, that most of the candidates have done the Test with Interpersonal or DLR before, same with the SIM and as Interpersonal does the assessment for EAT and I think also for Privat Air, all those guys did the test and the SIM that you just did a few years ago for another company and they are using these datas.
So it is not as easy as you say. But you are right, they take the people they know, which is not unusual for a start up company.