I didn't watch the full video, but at 6:45 it states
"Unlike most previously recorded car hacks, this demonstration was performed wirelessly over cellular networks. The vehicle shown is modified with third-party hardware for demo purposes. In stock form it is not vulnerable to these attacks"
which is quite different from the level of vulnerability showcased in the Wired article.
I'm reasonably sure that if they had tested in a private track and made a public article it would have the same effect as what they did in their post.
In essence, the publicity factor is the most important, not where they tested it.