Ok I'll admit I misread the original post as "why aren't koalas bears?".
But yeah you're right this does actually answer the question in the OP.
Edit: nevermind I didn't misread. This doesn't answer the question of WHY koalas are not bears. Taxonomic classifications have logic and reason behind them. So a proper answer would be that bears are placental animals with a longer gestation period. Whereas marsupials have a shorter gestation period and keep their young in a pouch. I'm sure an actual zoologist could give an even more enlightening answer.
My problem is just that this shows no critical thinking skills at all.
The answer given here basically amounts to "they are classified differently because they're classified differently."
As someone who lived on the northern US border for a long time this is a very easy question for me to answer without being racist haha.
The myth of Canadian politeness really stops at the border.