[devoply]

People on tourist visa by definition are not residents or citizens. They are tourists. You can't tax tourists. Imagine how many people would avoid certain destinations, I mean executives, if this was ever an issue. Many people "work" while being tourists. It would be difficult/impossible to force them to pay taxes for the weeks or months they spent in your country.

[atemerev]

While it's still complicated, many countries use the notion of "tax resident", usually defined as "somebody who spend more than 180 days / year physically at our territory".

While it doesn't help US residents, as they have to pay Uncle Sam wherever they live, many non-US people are using this loophole to avoid being taxed anywhere. Just find 3 countries with residence-based taxation, avoid staying more than 180 days in a year in any of them moving back and forth, and boom! Zero taxes.

(YMMV, IANAL)