I often go up to the staff after these incidents to reassure them that they did the right thing and offer myself as a witness if they decide to report abusive behaviours.

Even with my limited amount (subjective) of travel, I encountered two of these people alone in April.
1. After getting off the DUB-LHR-LAX and navigating through half of LA's population at TBIT, I arrived at Marriott Marina Del Rey. The lady in front of me went ballistic when asked for identification documents. She kept on blabbing about it being racial profiling, and she did not receive such degradation at the Ritz Carlton next door. She even pulled a 'Karen' and asked the manager to apologise.

2. My T3 flight to MRS was completely full in Y, and naturally, the gate staff started looking for bags to gatecheck. A tall man, presumably French based on the way he dressed and his accent, was unfortunately selected. The staff detailedly explained the terms in the contract, stating that only the personal item was guaranteed, but the French man had none of it. He even proclaimed, "I don't care what the terms and conditions say; you are not taking away my bag". As the man was ready to use his carry-on as a weapon, the staff backed down and asked other more reasonable passengers instead. As it was a bus gate and 90% of the passengers could not wait to be cramped into an A320, I waited until the end and chatted with the staff. When asked about the incident, they just shrugged and said this happens almost every day.