Dogs can only do so much

I was walking my dog the other day and and a neighbor's puppy came running down their driveway to greet us. No problem with that for me, but they they have one of of those Imaginary Fences, or whatever they call them, that are supposed to keep the dogs penned up by shocking them if they go past some imaginary boundary. But this dog didn't have the appropriate attire and so received no shock. So I rand their doorbell to tell them their dog was loose.

My neighbor came out and was grateful for the return but was fussing at the dog, calling it dumb and, horrors, bad. But as I was walking away, I was thinking, the dog wasn't the one who forgot to put the collar on, it was my neighbor. So whose fault is that exactly? I decided not to pursue it, but I have hypotheses.