It might be because an electronic payment system can accept exact tender and / or the options to tip defaults to lower payment options / easier to hide a small

It might be because an electronic payment system can accept exact tender and / or the options to tip defaults to lower payment options / easier to hide a small tip to your friends With cash few have exact change and the table can see what you give. This leads to rarely asking for change back and putting higher amounts as it ups your social ranking. This effect is easier to see in a bar. Often you need to keep track of dollar per unit sold as some staff will overpour