I don't think making codes human-readable would help -- human-readable URLs are spoofable too. For example, if you replace "tipme.com/some_bar" with "tipme.cz/

I don't think making codes human-readable would help -- human-readable URLs are spoofable too. For example, if you replace "tipme.com/some_bar" with "tipme.cz/some_bar", most people would have no idea the latter is the wrong URL; and even waiters/cleaners may not notice the change