It's just that shooting people seems to be the go to way of keeping the peace. Police officers want to go home to their families in one piece at the end of the day. The police have to kill people sometimes, it's just the way it is. Seriously though, it's really scary that the police can kill citizens with impunity. Apparently the police have no choice but to kill us in such alarming numbers. It also has the largest total prison population of ANY nation period, developed or undeveloped, I guess Americans are by nature a rowdy bunch. In raw numbers and by percentage of the population, the United States has the most prisoners of any developed country in the world. Just for perspective, the US kills citizens at 70 times the rate of other first world nations.
Here's a website that keeps track of the people killed by the police in the US this year.