The reason why they do that is because the banks charge the airline a percentage fee for each credit card transaction they handle, whereas for debit cards they charge a flat fee for each transaction (usually a few pence) - so a pax using a credit card to pay for a flight costs Easyjet more than a pax using a debit card. The trend in low cost carriers is that if you anything which costs the airline (ie pay by credit card, check-in bags) you are charged separately for it.

On fees, any fees, taxes, charges etc which the airline collects as agent of the airport, government etc. should be quoted and itemised separately, but fuel is just another variable cost to the airline so any increase should just be reflected in the fare.

The worst example I've seen of surcharges was a flight to the US on AC. The fare was quoted at 294.00 (Canadian Dollars).

But then came...

Navcan and Surcharges 43.60

And..

U.S.A Immigration User Fee 9.40

And..

U.S.A Transportation Tax 36.80

And..

Canada Security Charge 11.22

And..

September 11 Security Fee 3.36

Not forgetting..

U.S Passenger Facility Charge 6.04

And finally..

Canada Goods and Services Tax 24.43

Which altogether increased the fare by some 45% to total 428.85