It seems to me there are a couple of issues here. I don't think a shelter wants just any JoeBloe walking in one day to say "hey I'd like to help by walking your dogs". The shelter needs to know something about its volunteers though a criminal check might be a bit much. If someone has been volunteering at a shelter for some time so the staff knows them and now new policies are being put into effect, then the shelter should have some sort of informational meeting/handout for all its volunteers so they know what and why. And even when volunteers have been accepted, some mini-training should be included for handling dogs. Many shelter dogs have been abused so I wouldn't want a volunteer who grew up under the "old" system of training with spanking and collar yerking now handling a special needs dog. Actual certification for dog walkers - no - the government intrudes enough.
AJs Humana - you have a right torant. I too get annoyed about irresponsible owners.
We even get them at the shows here with Basenjis. People who say - "keep your dog away from mine" (this in the ring) "he/she snaps"!!!! Also others who wander past a crated dog with several of theirs on loose leads, poking at the dog in the crate. When the crated dog reacts they complain about bad temperament!!!
Actually - I posted it on the Podengo group - lots of members in the area and looks like might be something from one of the hunt packs (or a golden GSD mix) Maybe one of them will bite.