Just because we all share the same job title, does not mean we all do the same job. Someone has evaluated all the units and determined these bands. Should the Captain of a 737 working short haul, be on the same wage as a 747 pilot. Of course not, but they are both pilots.
Who has stated that we should all be paid the same?
The banding system is flawed and always has been. The initial study was not perfect, and the union at our pensions brief agreed that they may have made a mistake and that it contributed to the pension problem. That makes the lower bands who did not make significant gains feel really good.
If the big units continually get what they want at the detriment of smaller units then can someone tell me the point of the union? Isn't its role to look after the minnows and the collective as a whole?