Why should commercial airfields offer dispensation for weather diversions?
Because they can.
Here's an example of a well planned, including alternates, flight with a sudden problem:
Weekend
I'm flying IFR (in IMC) to, say, Coventry from Blackbushe.
North of WCO my anti-ice/de-ice goes wrong and I'm in cloud above freezing level - gotta get down. Now.
Cranfield, my alternate, the ILS has just gone inop or they have another emergency - rwy blocked.
Benson is closed.
Nearest divert is Luton - not put as an alternate because the landing fees at Coventry, Cranfield, Farnborough are all double digits not triple digits.
Should Luton accept me?
Should I have to pay > £200 for the diversion?