I was coming down my hill today, and some folks, working on a neighbor's project, had parked in the shaded part of the road on a narrow corner and they both had black cars. I could not see them at all given the angles of sunlight. I could only detect them because of the many times I had done this corner, and something was off. I didn't know what was off, just that something was not right. So I braked hard and then saw the cars, in the road. If I didn't know the usual signs, of the road, I would have slammed into one of the cars.
I stopped and said, I can't see you parked here in the shade. And they were very nice, and said, they didn't know they were invisible. and moved the cars soon after. No one was at fault here. They didn't know the cars, as parked, were invisible given the light conditions, so I'm not mad at them. Yet, this is how accidents happen.