You overestimate the chance of successfully disarming someone with a knife without receiving serious wounds.
You also overestimate the martial arts training most cops receive. If they're interested in martial arts on their own, they might be very good. Otherwise, a few months of training at any martial arts style that teaches immediately practical aspects like holds, joint locks, grappling, etc. will teach more than what cops know. It's not practical. Police procedure is designed to prevent officers from ever needing to get into serious hand to hand fights with criminals.
Most cops do not shoot violent criminals in the knees or shoulders because they are not that accurate.
In the Diallo shooting [1], 4 NYC police officers hit Diallo 19 times out of 41 rounds fired.
If a cop is a good shot, and is not under pressure, he or she can hit a suspect's knee. Most shootings occur under high pressure, and most cops are not good shots. Most cops qualify periodically as required under police regulations and that's all the firearms training they care about.
You also overestimate the martial arts training most cops receive. If they're interested in martial arts on their own, they might be very good. Otherwise, a few months of training at any martial arts style that teaches immediately practical aspects like holds, joint locks, grappling, etc. will teach more than what cops know. It's not practical. Police procedure is designed to prevent officers from ever needing to get into serious hand to hand fights with criminals.
Most cops do not shoot violent criminals in the knees or shoulders because they are not that accurate.
In the Diallo shooting [1], 4 NYC police officers hit Diallo 19 times out of 41 rounds fired.
If a cop is a good shot, and is not under pressure, he or she can hit a suspect's knee. Most shootings occur under high pressure, and most cops are not good shots. Most cops qualify periodically as required under police regulations and that's all the firearms training they care about.
[1] http://topics.nytimes.com/topics/reference/timestopics/peopl...