Water usage is probably my biggest. Living in a high desert, my wife and MIL see no problem with filling one side of the sink with hot soapy water to wash a few dishes because “that’s just how I’ve always done it”, to watering the grass and plants for hours. All of this makes me mental.
If you compare it to “have a good day”, it’s longer and awkwarder, and the extra words are to avoid…the scenario of someone complaining that part of the day has already passed and can no longer be nice?
In the same vein of unnecessary specificity: I hate when waiters ask “how is everything tasting?” I have to resist replying that it tastes great but it’s cold and the texture makes me want to gag.