That's the problem there mate. These idiots -- the kind not likely to train their dogs -- are drawn to breeds which are dangerous if not trained properly. They're not necessarily breeds that are more problematic (for example German Shepherds have an incredibly powerful bite but they're also immensely intelligent and are very easy to train) but breeds that require more responsibility. A Jack Russell that's poorly trained and a Bull Terrier that's poorly trained could be equally bad behaviourally, but only one will do real damage.
I don't agree with Brennan's attitude towards these breeds though. Some of them are fantastic dogs and much like things like alcohol aren't necessary for human life, but having one of these dogs is something that people have a right to, and something many people love. If you're responsible, it's fine.
It's just a shame these scummy dog owners aren't mad for Yorkshire Terriers. FFS.