AMEX
I think I have to disagree with you:
1) As I recall, BA do indeed assess your learning curve. Correct me if you know different!
2) Many pilots pass LPCs, and OPCs on their rated types, who aren't necessarily high quality. Hey, I might even include myself in that number!
3) Their 'experience on type' probably isn't important AT ALL to BA. The only reason they ask for A320 (etc) type rating is because it reduces the training cost! It is NOT the only type BA fly. No doubt many will bid onto an 'antiquated' Boeing (such as a B747-400) As soon as they can.
Better for everyone if their flying ability is assessed, before any committments are made? Saves dissappointment later, don't you think?