Good grief, you certainly didn't think they train these dogs about how to behave in large crowds without their ever having been around a large crowd.
You should watch cable TV also. Discovery Channel has "police dog" specials at least monthly.
Given the half-life of these dogs when it comes to being in top physical and mental form, they need to be replaced long before their useful life as a dog is over. Many people are happy to get a well-trained, obedient, dog when that time comes.
Again, it is not necessary to live cheek to jowl with dogs up to your eyeballs to know something about them or to observe the obvious.
(You should watch cable TV also.)
I’d rather rely on my own experience with canine patrols. My last year with the SO, we started 2 canine units.