My husband is Australian and whenever family visits from there, they most certainly buy travel health insurance. It can be very expensive if they have health issues. One family member had a previous stroke and another previous heart attack and travel health insurance was more than their flight over. And that was only for 1 month.
But, it's definitely necessary. One visitor we had (and she was young, only 21), had complications with a UTI (she wasn't resting enough) and ended up in the ER. Her bill was over $9000 before all the Dr's charges had even come in. I had to call her Dad and explain it all to him. Thank goodness she had travel health insurance though!
Julie