The same goes for buying a holiday, even airport parking - a premium if you use credit cards!!
not jumping to their defence, I detest them as much as the next man. They are just passing on charges levied by the credit card people. Where this is outrageous is if you pay by debit card, the 2.5% is swallowed by the retailer. EG Boots. When you pay, there is a bit on the receipt that says 2.5% goes to boots card services, but the total paid remains the same. Which is more open and acceptable.
Once a company starts sneaking this charge on to credit cards, there's no turning back. A few people pay and a precedent is set. If everyone had stood up and said "NO FKCUING WAY" at the start, we wouldn't have got where we are.
No longer accepting cheques is about liability, nothing else. Under english law, if you sign something like a cheque, it is legally binding, and the onus is on the person accepting the cheque to check the signature, all at their risk. If the signature doesn't match,and the transaction bounces, then they have to bear the cost of the lost money.
However, with chip and pin, it's a new law. The law states that knowledge of the pin is deemed sufficient proof that the card holder is who they should be. Thus liability passes to the cardholder, not the retailer, who must bear any losses if the transaction was guaranteed with a pin.