Say what you mean

If there’s one phrase I can’t stand, it’s “have a nice day”. Oftentimes you don’t stop to think how illogical it is to say this to a complete stranger. You have absolutely no clue how his day has gone, and absolutely no control over how his day will go. You can express a hope that that person will have a nice day, but you have to indicate your hope in order to make your sentiment clear. When you just say “have a nice day”, that turns the phrase into a command. You can’t command anyone’s day to be nice any more than you can live without breathing.