Well guess what... dog training is broken and we have to fix it.
Every day, dogs are euthanized due to behavioral problems. Dogs that could have had beautiful, joy filled lives are cut short because they couldn't become the dog the owner wanted.
And it was little to no fault of the dog. It's a fact that it is not overpopulation that is causing dogs to die in shelters. It is the problem of families giving up on animals because they cannot solve their dog's behavioral problems.
People try their best with the tools they have, i.e.: the experiences and muddled mimicry of the training of their past dogs or the inconsistent, want-results-yesterday expectations that will inevitably doom that dog to fail.