The big difference is that, while I'm fluent in Dutch and have VG English and French, I (training at SFA) can apply as an ab-initio and have a fair chance with AF, BA, LH (if I learned german), but never with the KLM, because no KLS/NLS/KLu training, no interview. The point is that you don't even get a chance to apply. With LH or AF, you learn the language and can apply with any JAA license, fair chance for everyone. With KLM, even though my training is pretty much comparable (KLS even trains its students with us (SATC) in Phoenix in the same programme), I don't have a fair chance, in fact I don't have any chance.
edit: and I think learning a language of a certain flag carrier is no big deal compared to just having no chance because of your FTO choice. It doesnt seem abnormal to me that, for Air France, you have to speak French.