In a Bitcoin future, the delivery guy will have a QR code on his sleeve/cap. U can instantly tip there. Moreover, tip is not 'mandatory' anywhere !!! If it is mandatory, it is not a tip, it is the price.
There are lots of places that have an automatic "gratuity" worked into the bill.... I have removed it from the bill before now due to staff attitude, Sir you obviously frequent the lower end of restaurants!
