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.
While many people do say that to simplify, the singular they has been in use for centuries. If you see a person’s silhouette in the distance and you want to talk about something that they did you will you they/them pronouns for them in most dialects of English.