My boyfriend has just signed up to volunteer at our local shelter, and he's expressed some similar frustration by the bureaucratic process. He's gone to a 2-hour orientation so far, and there's at least one more dog-specific orientation that he has to attend before he can sign up for walking shifts.
I tried to explain that they're just trying to cover all their bases and it's not a personal slight against him if they can't tell the difference between him and any well-meaning but possibly dog-illiterate guy who walks into the shelter, and that a little bit of hoop-jumping at the outset just makes things easier for EVERYONE in the long run, especially the dogs. But I haven't thought of the best way yet to explain the necessity without resorting to specific scenarios that may or may not apply to something that might happen when he's out walking the dog. Our shelter is in a semi-urban, residential/commercial/industrial part of town. I don't know where they're allowed to walk the dogs yet, but it's very likely that they will encounter other people, if not other dogs and dog walkers.
I see how people misread dogs ALL the time. Both of my dogs are quite friendly with people, and they'll walk right up to strangers to sniff and check them out, especially Bowpi – but they immediately duck away if the person reaches down to pet them on top of their head. Do that to the wrong shelter dog, and he might bite instead, instantly jeopardizing his chances of adoption. Another one is how often people figure that wagging tails and eager, pulling dogs are not just friendly, but expressing a healthy "curiosity" towards other dogs and they should be indulged for their "extroversion." But it's a terrible habit to encourage for a million reasons...
I'm probably ranting to folks who already understand. While it sounds extreme to be "certified" to volunteer to walk dogs, it doesn't sound out of line to me to require just a few hours of training and pre-approval in order to work with living creatures in somewhat unpredictable settings.