If they were serious about reducing airport congestion- they could agree to donate the £4 per car to a public transport fund to finance a decent local bus network to/from the Airport. Now that just might reduce congestion around the Airport, not just the terminal forecourt.
We know it's about making money and they don't really want to do anything that would affect the car parking cash cow.
STOP PRESS:
Maybe I spoke too soon.....
https://www.manchestereveningnews.co...igure-14440012