[adamomada]

Why do you consider Wikipedia and Wikipedia only? It took 2 seconds to see a different definition that fits from my phone

> persuade (someone) to act in one’s favour, typically illegally or dishonestly, by a gift of money or other inducement

[gruez]

How is pre-tipping illegal or dishonest?

[adamomada]

It doesn’t have to be, you can consider it atypical bribery if you wish