God bless 'em, they'd have a cow if they saw what some people in Asia and the Middle East actually get away with taking into the cabin.
I remember once queuing up for a Middle East carrier, watching people taking case after case and oversized box after oversized box on board unchallenged.
When I got to board, the rather ineffectual lady at the gate then decided (or had more likely been told) there was too much hand luggage on board, and tried to tell me that my military canvas bag of nothing but clothes, weighing about 3kg, was too big to go on board. When I demonstrated how tightly it actually compressed, she was still adamant that it wasn't going on board, because there were "too many passengers".
When I explained just how badly she had done her job, and read out the airline's ground service manager's name and number from my phone, she sped off into the distance and one of her colleagues took over.
For every unthinking passenger that does this, there's an unthinking airline/airport employee letting it happen, so they both need to be addressed.
And I use the word unthinking in place of more derogatory comments.
And I do pity the CC who are usually the ones left trying to get a square peg into a round hole (which is probably where the bags in toilets thing comes from).