much BEA BOAC rivalry
Spoke at length some years ago with an ex-military pilot who had joined BOAC and progressed to become a BA Concorde Captain.
His view was that the operations too were "chalk and cheese". These were the days before cellphones and email; once beyond Europe - certainly Eastabout - the captain was very much "sole proprietor" and couldn't easily 'phone home to sort out problems.
In his view - I have no non-military piloting experience - it was that difference which attracted him to BOAC rather than BEA when he left the RAF. So perhaps the different operations attracted different "types" who would then perpetuate the differences.