There is no obligation to give your VAT number. But many do because you have a tiny chance to win a lottery. Yes, they do it even for one coffee (0.70 euro...)

There is no obligation to give your VAT number. But many do because you have a tiny chance to win a lottery. Yes, they do it even for one coffee (0.70 euro...). I do not understand why there is still no system to easily transfer that fiscal number. For example with a qrcode or RFID. You pay electronically with card, often only by just touching your card, phone or even watch, but then have to give a memorized 9 digit number which the deskperson has to type correctly.