What did they do, go toward Barney with their palms open, make quick movements, have voices like banshees? Dogs are smart when it comes to discerning friend from foe.
Barney, just doing the job his master won’t do.
Tha is my bet..you never approach a dog or cat for that matter with an open palm..To them that is threatening. These obvious non pet owners need to learn to extend the hand in a non threantening way and let the animal sniff them and then maybe the pet will allow the human to touch said furlette.