I think the major problem whether it is BT or any other massive operation is that when an organisation becomes so large individual accountability becomes lost, vast ranks of poorly paid and ill-trained people read scripts and if a problem is more difficult or unusual than the run of the mill it is very difficult to get the problem brought to the attention of someone with the ability and the authority to sort it.
I think that summarises things nicely in a nutshell, and the above applies irrespective of industry too (large airlines etc.).