An idea, however the advantage I see for this qjacker system is that it doesn't only remove the need to purchase, it also tell the servers how much they need to have ready. If the stock is there immediately to go (15 x Beers, 12 x Hot Chocolates, 9 x Burgers etc) then they can be at hand and ready to go. That would really speed things up, show ticket, get goods, go. Ten seconds rather then 30. Contactless cards will only remove the need to organise money, there would still be added time to put the items together.