I distantly recall that canon!Hermione was trying to remove her parents as potential hostages / revenge targets. I think the goal was to get them to Australia without violating the Statute of Secrecy. This doesn't make sense, now that I think about it - her parents already knew she was a witch, why is telling them about the war a violation of secrecy.

I suspect this is because they wouldn't voluntarily abandon their daughter, this was her way of pulling a more hero than thou on them.