If tips these days are mandatory, it is still false advertisement to say FREE delivery.
No, that is not false advertisement. It is free altz the store. It is common knowledge that “delivery” means you should include a tip whether it is called free or not.
Unfortunately, this “common knowledge” is not so common among the few stereotypical cheap, “frum” Jews who seem to frequent this site under many screen names.
It is common knowledge among ehriche yidden who understand concepts such as derech eretz and hakaras hatov and that other people are people too, whether they are Jewish or not.