Degree difficulty very low. eta: And, the person's big bad reaction to constructive criticism is why I don't comment as much anymore.
There was only Criticism, nothing at all constructive. You stated as fact an opinion that was disproven, that's all.
Had you said... "I voted this a 1 because I feel it wasn't difficult to achieve" (which should not really be a factor), that would have gone a lot farther than coming along after the challenge was over and opining incorrectly.
1. Camera mounted to tripod ballhead.
2. Ballhead mounted on Monopod.
3. 8mm Fisheye Lens attached.
4. Wife driving car at normal speed as we take our dogs to park.
5. Set timer mode.
6. Press shutter.
7. Photographer risking his camera extending the whole thing out the window, away from the car, fighting wind resistance.
8. Repeating several times and angles to get a good shot that didn't show camera and monopod shadow on car.
9. Annoyed wife by embarrassing her to no end to oncoming motorists.
Yes. Very very low difficulty.
Kinda like shooting a non-moving landscape or a bucking ram from the safety of your megazoom lens.