What overseas carriers do which BA cannot do is transfer passengers from regional airports on to other destinations through their hub. I'd be interested to see just what proportion of Emirates passengers from BHX actually end their journeys in Dubai and how many transfer onwards. Ditto for Continental from BHX and Singapore Airlines from MAN, etc etc.
HZ123 - the BHX- JFK route made a very healthy profit when it was on a 767 because of some lucrative cargo contracts. The freight more than paid for the flight, any passengers on board were a bonus. It was only when the 767 was swapped for a 757 and we couldn't carry cargo that the route went down the tubes. Also, the flights were crewed locally, with BHX cabin crew and pilots from the dedicated group of regional 757/767 pilots based at MAN.