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.
Very true.