This could create a legal minefield as you are hired by these airlines after the endorsement. There is a disconnect between your endorsement and your employment. I think there was a Jetstar pilot who tried to sue recently after passing the endorsement and failing line training.
Also it is the training provider who is issuing the endorsement not the airline so how can they provide an endorsement stamped by the training provider yet not to their procedures but to one particular airline?
Could make for some interesting times with the whole 'pay for endorsement' scene.