Yes, it's very strange to me too as another European (although I did want to pay the tips and not screw the workers, of course).

Not that I like tipping systems at all, I find them an unnecessary hassle for the customer and detrimental to workers' rights, but if you have to have it I found the system in Canada (at least in Vancouver) much saner: you could key the tip amount into the POS machine when you pay, or directly select a tip percentage and the machine would add the tip for you. Compared to that, having to actually calculate the amount by hand and write it with a pen in the restaurants in New Orleans, blindly trusting that they would eventually charge that amount, looked like... last century.