Not a European expert by any means, but I've found that when you pay with CC there usually isn't a place to leave a tip. Tipping is done with spare change left on the table.
Also, I thought tipping itself isn't necessary, as many european countries have social programs to offset low wages.
The ideal solution here is to get rid of tipping, but I don't see that happening in my lifetime.
The ideal solution would be to tip adequately so that one doesn't have to be embarassed during payment.
In the American model, payment is processed away from the customer and the bill is left for tip-adding after the server has left, to save the sensitibilities of cheap customers who tip badly.