I got a black eye from falling this winter. I slipped on the ice, and had both hands full with bags of groceries.It's very, very hard to get a black eye from a fall, at least not as an able-bodied adult. If you trip forward or sideways, you will instinctively brace yourself with your arms in the time it takes to fall to the ground. You still might get a scraped temple or on the side of your face if you hit the pavement with your head, but in order to get a black eye something (like a fist) has to hit the socket directly. Pierre Delecto is a filthy liar.
I suspect something weird is going on with the cases pictured, but I will say it is possible to land on your face if you are carrying something and are too slow in dropping it.
On second thought, it was kind of a freak accident, so you're right that it's hard to do. I told people the truth of what happened, but I enjoyed having them think I had actually been brawling.