These things are omnipresent in European capitals, it's quite striking. It might be inconvenient but it's not gonna stop people any more than the privacy concerns of the apps do.
That being said, it is cultural norm here to tip by rounding up the order(say total is 2.59/ you tip by asking to make it 3.00/) when you are ordering in person and the service is/was good and the food is/was also good quality. Alternatively, in some restaurant, it is not usual to tip as order is collected by someone near the cash register while served by someone else entirely and someone else is preparing it. Once you are done eating, you return the dishes and go home, so there is no option to tip as you simply don’t tip at the prepayment step because you don’t know the food and service yet, you don’t tip the server as they simply bring the food and walk away.
There is already a tipping UI in the app, but it is not intrusive, nothing as aggressive as what you'd experience in the US where you're inclined to pre-tip even before the delivery happens.
As for the capitals, yes it is becoming a thing but from my personal experience it is limited to touristy places