Just to clarify one point, card imprinters might now be pointless but I do personally think they were a brilliant solution at the time. They are so much quicker (and more accurate) at recording the account details than someone handwritting them out. So while their time has come and gone, hats off to whichever individual(s) that came up with this idea in the first place. It was a brilliant little hack.
[And yes I am using "hack" in it's more traditional sense]