I didn't mean to equate the two (violence and rudeness), I was just making the connection that the one leads to escalation of the other. I suspect it's not as if a passenger just runs up to an airline staff member and punches them, a propos of nothing, out of thin air. What I can see as a much more likely scenario is that the staffer acts in a manner the customer doesn't like, the customer curses at them for it, the staffer yells at them, etc. And this can be minimized by offering way more customer service training than it seems like most airlines have. I fly very frequently, weekly usually. And I see and experience absurdly unnecessary rudeness all the time. Another, relatively minor, example from a few weeks ago: when a plane landed, a woman stood up while the seatbelt light was still on. The male flight attendant snarled at her "SIT BACK DOWN, RIGHT DAMN NOW!". Screaming and cursing at customers is not acceptable, and again it doesn't justify escalation, but it certainly creates the breeding ground for it.