Alexander Litvinenko ISTR a few years ago when they tried to pilot e-cash cards to speed up transactions (in the Upper West) the HNA massive condemned that idea for every reason under the sun ....
ANd what happened to those? Just asking as had no idea.
Vouchers are a different thing though, no doubt would be complaints about losing them, or people in front with a voucher for a beer, another for a lemonade, then paying old fashioned cash for everything else.