As an aside, kangaroos in motion are one of the most efficient and elegant mammals. I love watching them bounding away at speed effortlessly dodging scrub and trees - more like flight than running.
I grew up in Alaska and when you ran into a moose you weren't allowed to keep it. Instead there was a volunteer crew that was called to clean it up, compensated with the corpse (which is how I grew up on moose).
- health: most people don’t know how to process raw meat or recognize a sick animal (rabies or other illnesses)
- safety: those animals are tough, it’s not uncommon for boars to wake up from the concussion before, while, or after being loaded in a car, and the last thing you want while driving is a wild, fearful, angry animal suddenly waking up and ripping your car apart from the inside while you’re driving (happens).
- law: hunting is regulated so as to control wild animal population growth, killing some has to be reported one way or another.
I suspect there is another historical reason, akin to why you can be prosecuted for attempting to obliterate your own existence: your own being is basically owned by the Republic (used to be the King), so committing suicide is a prejudice to the State. I can see something like this being in effect: wild animals are a property of the State, and killing them even with your car is poaching. That may be why you’re supposed to turn the corpse to the Gendarmerie (cops branch of the military).
(IANAL, correct me if I’m wrong, that just what I’ve been taught as a kid growing in a rural area full of forests)
Also you can get kangaroo meat cheaply at most butchers. It's just like venison.
Of course, that is assuming you are still OK after hitting one - Kangaroos are BIG critters and can do considerable damage to the vehicle (and occupants) in a collision.
It is quite divisive though, some people enjoy the taste, myself included, but others have a strong dislike. It is high in protein so often enjoyed by gym-going types.
Wallabies are like 1/5 or less in size/weight when compared to kangaroos, they are small animals I would say comparable in size/weight to a large rabbit.
The car was a not so small car, a Holden Torana, a V8 4.2 liters, if I recall correctly, still the hit was very hard and the australian guy that was driving didn't manage to keep the car on the road and we ended up in the field nearby.
No physical harm to anyone on the car, but the fender and front of the car were seriously damaged.
I wouldn't have wanted to have hit a full-sized kangaroo instead of the poor little wallaby.
This was in an environment where daytime temperatures are often 40C (104F) plus during the day.
But Roo's need to be bled properly otherwise the meat goes to hell. You can get away with eating fresh tail, but really a roadkill roo wouldn't be very nice.
Plus, after 30 minutes in the sun, it'd be no good for anyone other than the flies.
The hopping movement makes it incredibly difficult to judge their speed and direction. They actually cover horizontal space at a far greater clip than they seem to, and also means they can make snap changes in their direction of travel VERY quickly, making any avoidance manoeuvre a bit of a wild guess.
Unpredictable motion is ideal for evading upright preditors with spears, but no so good for collision avoidance with fast moving metal objects.