I’ve forgotten the exact context, but low skill job could just be brutally honest. I do agree that waiters do have to learn tact to handle different moods, rudeness, entitlement, etc.
And some waiters are proficient to the point of being quite lucrative. Having said that, entry level order taking at fast food places, assembly line where you place a handful of parts into an overall assembly, lawn mowing…those are truly low skill jobs. Not that you would lord that over the people that did it, because that is rude, but it is also objective fact (in my opinion).