Commentards blaming the phone users (well - they were stupid enough to buy Apple) are obviously not Australian, or have never left their major city.
If I have an expensive device equipped with a GPS that's touted as a feature, I actually expect it to work. Unreasonable? Maybe. People were unreasonably expecting that the iPhone4 would work as a phone, but failed to realise its not a phone, it's an iPhone, whatever that is.
Seriously though: someone earlier said something about paying attention to the locals. Clearly from ol' blighty - no idea of the distances involved in Australian cross-country driving, or the fact that you can go from a full tank of petrol to empty without seeing another soul. Then you're screwed. You didn't get the chance to ask directions.
Yes - they should take precautions. They should also expect that their feature-packed phone which is heavily advertised as having a GPS is at least somewhat reliable. 200km off is not reliable. In the outback, that could be the difference between life and death.