First off, I know that you are an experienced decoy and work your dogs, I hope you didn't take my post the wrong way. I have watched your videos, seen the pictures and have a great deal of respect for what you do.
A Police K-9 absolutely needs to be stable enough to work in crowds, do foot patrols and even do demos for kids. With that said, the K-9 does not need to be so social that anyone can run up and pet it. I have done hundreds of demos with my dog and I always have to tell "little Johnny" that he can't pet the Police Dog. Heck, I was cursed out by one guy for not allowing him to pet my dog. My dog was calmly laying on a sidewalk at a hotel as I talked to another cop. This guy came up, complimented the dog, asked his name and then proceeded to try to pet the dog. My dog never budged, but does not like strangers touching him. I explained for liability reasons that we do not allow citizens to pet our dogs, that the dog bites and our Policy and Procedure doesn't allow it. I was told that "all dogs love me" and "that dog won't bite me!" Then I was told I should have better control of my dog and all Northerners are a**&@(#@s. Since the dog remained in a down for the entire 10 minute rant, didn't move a muscle and was calm, I felt like I had pretty good control.
Patrol dogs need to be clear headed, first and foremost. Dogs that are as driven as I like and with the propensity to bite in prey, fight and defense need to have a strong temperament. You are on the precipice, with a delicate balancing act. Too much drive and aggression without a clear stable mind and you will wind up on the wrong side go the edge. Without the drive, but even with calm nerves you are on the other side, working a bit of a dud. You need the balance and you need both, for sure.
Dogs that can not be around people have limited value and use. I take my dog out of the car on almost every call I go on. he wouldn't be much good if he needed to stay in the car. I also work my current dog on the SWAT team, which really requires a clear headed strong dog. No one wants a dog that will take operators on an op. I have sent my dog upstairs on a covert building clear, had him check rooms and downed him in the hallway to watch a room or downrange. I usually do this from the stair well or even down stairs. The team flows up into the rooms the rooms cleared by the dog. Guys have stepped on my dog going through a door way or down a hall and he doesn't react aggressively if at all.
I do not like Handler Aggressive dogs, I do not like fighting with dogs. Handler aggressive dogs do not run faster, bite harder, search better than any other dog. They are more of a PITA though. I see no advantage to HA dogs and when I test and select dogs I avoid those for out unit.
I'm not sure what trials you were referring too? As far as dogs getting "ran" on the field, it can happen. It can also happen to any dog. If I wanted to run a dog, regardless of how tough and strong he is, it can be done. I don't do it, but the right situation, the right stress and pressure and any dog can be made to bail. We do not do any "trials" with our K-9's, only certification. It might be fun.
"Dogs biting partners," LOL it happens. I've been tagged once or twice on the street. Recently, at the end of a 45 minute two city pursuit at well over a 100 mph. My buddy latched onto my thigh and gave it a good squeeze. It was the other cops that I was worried about. He was pumped and wanted to bite some one, it was a target rich environment for the dog. To Boomer's disappointment the bad guy fell into the thickets bunch of thorns, briars and bramble that I have ever been in. Wrapped up like a briar burrito, the armed robbery suspect gave up.
Any dogs that have weak nerves or temperament issues should not be Patrol dogs. It is easier said then done.
I'm also not saying that GSD's are not good Police K-9's they most certainly can be. But, IMHE it is getting harder and harder to find suitable GSD's that meet my standards. There absolutely are excellent breeders producing very good dogs, but these are not dogs that I see for sale from vendors. I can easily find a super GSD for myself for IPO and a pet, I have one now. But, rarely do I see these dogs offered for sale through vendors.