I worked LAPD from 1971-1994, when I retired on a disability pension. When I started 90% of my academy class were vets and over half had been in the Nam. We knew firearms and a bunch of us were shooters away from work. In 1974 the courts mandated that we hire females. Very few of them enjoyed shooting and they had to have extensive training to meed qualification (and physical fitness) standards.
Over the years the percentage of recruits who have previous firearm ownership and use has declined, making the range coach's job a lot harder. However, they do have to meet the minimum qualification standards and L.A. has so much action that drawing your firearm is normal and being under fire, and returning it, happpens to most street cops.
The low hit rate is often cited as evidence that cops are poorly trained. Remember, this is not the range. Shootings take place at all hours, many at night, with reduced visibility. The target is moving, not stationary, and the fact that he is shooting at you does tend to hamper your marksmanship. And while many suspects are prepared and know what they are about to do, the average cop walks into the situation with no advance knowledge.
The North Hollywoood shooting is a goood example, however, of what can happen when officers have a minute to react. Yes, the 9mms were bouncing off the suspects' body armor, but officers became aware of that and if you remember the video, they were starting to stalk the badguys to get closer, for more head shots. Even if SWAT has not arrived when they did, I firmly believe the suspects would not have lasted 10 minutes longer.