I seem to remember in the early 70's when credit cards were introduced, it was against the law in the UK to charge extra for their use. The banks soon "convinced" the government to change their minds.
Tony
My memory is that it was the other way around. The banks successfully petitioned to make it illegal for retailers to charge more for accepting their cards. The law was later repealed.
The problem is any such law is not really workable as anyone paying cash can simply ask for a discount.
~iw
