[justinpowers]

This may just be a side-effect of the insurgence of new POS systems and customer-facing systems.

Many of the newer POS systems were first developed with the hospitality industry in mind. In those cases, tipping is on by default. These POS systems have since expanded into retail and convenience stores, leaving tipping on by default. The shop owners have little incentive to turn it off, or may not even know how to turn it off.

Additionally most older POS systems were not operated by the customer and so did not display set percentages. They relied upon manual input based on a signed receipt. So percentage norms were mostly word-of-mouth. Nowadays, with customer-facing POS systems, it’s easier to just provide a percentage button. And the owner or manager or even the lowly register attendant, can adjust as needed. And of course, higher defaults are better for all of them (within reason).