This is an extreme exaggeration. Large animals (mostly deer) that are road kill are quite frequently eaten by people but most roadkill are eaten by scavengers. In many places deer or occasionally other large animals are given to charities but, while not uncommon, it is hardly the norm. Survey county prisons in the US and you will find less than 15% feed roadkill to inmates. Most roadkill is small and not worth the bother. If someone hits a deer it will in all probability be eaten but almost all opossums or groundhogs are left alone or occasionally picked up by county or municipal services for disposal. People hit elk and moose and other game animals that are then frequently eaten too. I have a feeling if there were kangaroos or wallabys here many of them would be consumed after being hit but obviously this is guessing.
Now I get to tell a related personal anecdote. A friend, Todd, was driving to his new home in the far flung suburbs about 35 miles from where he works. It was property once owned by my SO's family as a working farm but that's a different story. Anyway on his way home at dusk this strict vegetarian friend and his son hit a deer. It was not killed but broke its legs. A local person in a pickup pulled up behind only seconds later to see what had happened. He took his rifle out and shot the deer and asked Todd if he wanted it himself or if he could take it. Todd, was telling some of us this story and he commented how nice this guy was to put the animal out of its misery and even put it in the back of his pick-up so he could put it in the local landfill and save Todd the trouble of disposing of it. You can imagine the hysterical laughter this prompted. It took a bit of convincing before he believed this guy was going to eat it. He just couldn't imagine why anyone would do that.
John Thornton