The humble Air France cabin attendant/gate agent has far more pressing worries than policing Europe's skies. Like making sure that the passenger has boarded the correct aircraft, and that the passenger's ID matches with the name on the boarding pass (even if that last task has now been removed).

Air France staff are not, and should never be, the last (or only?) line of defence in apprehending fleeing criminals. To suggest that boarding ID checks are a vital security feature, and should be retained for their usefulness in detaining fleeing criminals, is either naive or laughable.

As suggested above, if the criminal is "fleeing" to another Schengen jurisdiction (which isn't really fleeing at all) then they could just board a train, where ID is never required, or live up to their reputation by stealing a car and driving over a national border. If they do try to leave Schengen, well they will have to submit themselves to passport control (I believe this to be true at most exit ports, anyway).

But the hardened criminal will always be able to slip away unnoticed - whether by land crossing, or piloting a small craft (whether by air or by sea) to an unpoliced entry point in an non-EU country, from where they can make good their escape, foiling Air France and Interpol in the process!!!!