All that practice shooting tail-wagging, 15-year-old beagles finally paid off.
Yes, I know labs are wonderful, but a 100+ pound one broke the skin on my arm through my Carhart coat. That's one heckuva bite. Scar is still there. It had my long-haired dog by the neck as I was trying to separate them. It was flipping my 25-pound dog around by the neck like a play toy. The long hair saved him since the lab had a mouthful of fur instead of meat. The owner, a friend, had him on a leash and was barely able to pull it away. He didn't train the dog to be mean or to attack. In good weather it sits in the front yard with not tied up. It just decided it didn't like my dog.
Years ago I was bit on the leg by a lab as I was riding a bike in the street. It was out with its owner and as I went by, it ran out and bit me. The only dogs that have ever attacked me or my dog were labs.
A properly trained dog should be loathe to disobey a command, especially on a leash.
The number of dog owners who can actually control their animals is close to 0%. Dogs are stubborn, willful, and dangerous creatures which must be dominated by their owners. But that takes a commitment of time and effort. Most people buy dogs when they are cute little puppies, then ignore them.
It's a shame, but if a person isn't willing to do what it takes to be the alpha, he should stick to cats or goldfish or something.