Have you ever been involved in a real-life firefight? Bullets coming at you fast & furious? You’d only hit 1 out of 5 shots too........it simply ain’t the firing range where you can take your time getting your sight picture.....
Most cops probably practice far more than you......or me - and I have my own range on my country acreage in front of my house.....
The civilian members of that range get far more practice than the police get, and are considerably better shooters because of that.
Target shooting is not combat shooting. I get that. I have never been in live-fire combat. I doubt that I would do very well in combat. I know people who did and I tend to trust their opinions.
Police shootings are not the same as Military combat. Most police shootings are at less than 20 feet, use fewer than 8 rounds and last less than 10 seconds.
The training and equipment that Police like may not match up very well with what they actually have to do.