For the same reason that matte asphalt will become a mirror for oncoming headlights in the rain? A film of water on a smooth surface will produce intense reflections, even when that surface is non-reflective when dry.
The picture shows a lambo after a storm, parked, in daylight under cloudy skies. Your video shows a lambo driving, at night, during a rainstorm with flashing colored lights everywhere. You need to redefine your experiment better.
I had a 1988 Ford Bronco painted matte black and when it was wet it was glossy like a regular paint job. This happened in rain storms and when washing the dirt off of it after it had a big off-road journey.
if i had the ability to start the storm and stop the storm on stand by i would. anf if i could have found a matte car at night in the wet i would have posted it instead.
You can match the conditions in forza horizon to those of the picture. It rains a lot so just drive it through a storm and pull over on the other side of the storm and snap a picture, that way your comparisons will be very similar. But what was mentioned before about wax is also very true. The Lamborghini from the photo probably had a $300 detail job with a solid layer of wax over the finish which will make the water bead up and run off. There’s no way to know if the cars are waxed or not in horizon but when no wax is involved water will “sheet up” and create a glassy surface as it runs off the car.
Actually, you’re showing something else there, snakeheadinvade: the power of a good coat of wax. The water beads; it doesn’t create an even film. I’d bet that old Bronco markvii1 had wasn’t waxed at all. I’ve had some old beaters myself. A certain dull-green Buick Skylark comes to mind . . .