Well, I wasn't airline staff, but I worked airport security. And for what it's worth, I was really lovely to our passengers. I was always mindful of the fact that not everyone was a regular traveller. That the security rules were stressful and confusing for some pax, for any variety of reasons. That they may have had to sit in unexpected terrible traffic en route to the airport, or their bus/train was delayed, and so they were stressed and in a panic. That not everyone was travelling for a lovely holiday, some were flying home to see a terminally ill relative/attend a funeral. I understood that travelling with small children was hugely stressful for pax, so would entertain their toddlers while their parents were being frisked, chat to their older children who were curious about, for example the metal detectors. I held many a baby while their parents were going through the metal detectors, having their bag searched etc. I very often spent my half hour lunch break walking pax who were a bit lost and bewildered by the airport layout to their gate, or back to the main desk at security where all left items were put, so we could check if the passport, or wallet, or watch that they'd left behind was there. As of course, someone in a uniform walking through an airport is always going to be stopped by pax with questions. And I certainly wasn't going to say "no, sorry, I'm on my break, go to the information desk". I also had lots of great chats and laughs with pax. That was very long winded, but I just wanted to point out that all airport security staff aren't stern-faced or difficult or unreasonable. All the staff on my team were the same. Though in fairness, our training period involved a good bit of customer service training, as well as the obvious training in the actual security aspects of the job.
That being said, the one thing I used to want to yell was "yes, water is a liquid". As despite the fact that we had what in our airport was called a 'loader', a staff member who would help pax load their belongings into trays, explicitly ask if their luggage conatained any liquids, aerosols, gels or pastes, remind them to take off their belts, remove wallets from arse pockets etc. Many times a day a bag would be pulled for searching, and we'd have to explain to the pax that it was because the x-ray showed a bottle of liquid much larger than allowed. To which they'd respond "yes, but it's just a bottle of water". Ah yes, but water is a liquid! That was the one thing that used to get on my wick.