All killing is bad. But I have a story that is somewhat relevant.
I was in Denver last summer for work. When it was time to fly home, I walked down to the trains near the Union Station building and bought a ticket to the airport. When I got on the train, it was about half full and some crazy homeless looking guy with a machete tied to his waste also got on the train. Luckily, a cop was on the train and told him that he needed to get off the train. The homeless guy yelled, "EFF YOU" and stayed on the train. The cop replied, "John, you need to get off before I call for backup." The guy walked off the train and we left for the airport.
I guess my point is that having a transit cop in the train who knew what and who to look out for made everything safer. Maybe people don't want this job? It seems like it is needed. Way more that 180,000 more IRS agents.