Litebulbs.
It is a doddle. Easy, simples, and hundreds of private sector companies do it every day.
it isn't always completely "fair", but then nothing in this world is completely fair.
Quite simply, performance targets/behaviours/survey feedback etc are set. Good ones get it, not so good ones do not.
Great Co.s fire 5% to 10% of their low performers each year. BA have not done this with CC and should have done so 20 years ago.
Then, we customers would not be faced with the heritage CC attitudes that some of the CC from lhr produce.