Tipping is a thing in Eastern (to be more accurate: Central) Europe too, but where I live, tipping is not taxed. Actually, let me be more accurate: people who pay with credit card always tip in cash, as there is no way to tip with a credit card[1]. :P If you buy anything with a credit card, the total amount must always be identical to the sum of the prices of the products, it can never be more, so cannot include tips[1], which forces people who tip to tip with cash.
Food deliveries (similar to Uber Eats in the US I suppose) have the option to tip, and 100% goes to the courier. 200 HUF (0.57 USD) is the most common amount (as per their website[2]). We do not use percentages.
[1] It varies and might not be universal.
>>Actually, let me be more accurate: people who pay with credit card always tip in cash, as there is no way to tip with a credit card.
Eh? I don't know if you consider Poland eastern europe(I don't really), but I tip with a card all the time in Poland, you just ask "hey can I leave a tip on the card" and they bump up the amount by whatever you want to tip. And no, the amount doesn't then equal what's on the receipt - I don't know how they work it out internally, but frankly that's not my problem.
"Cash is untaxed" is a universal rule; there's a food stall that only sells deep fried Vietnamese eggrolls (and has for decades), they prefer cash; in part because cash is untaxed and they may forget to document every sale on occasion, but also because they do relatively low amount transactions (<€10), the €0.25 transaction fee does add up for them.
It's also why "knowing a guy" can be useful, tradesmen coming in on their off hours to do a job for cash.