Only a data point of one, but I'm surprised there's no(?) mention of humidity. Dark clothes in a dry and hot desert versus dark clothes in the US South / Florida where it's regularly 90F+ and high humidity is a very different beast. Light clothes that wick away moisture is a must in the latter environment.
As far as fashion is concerned, I cannot be bothered to care. But I found the discussion about black clothing keeping you more cool to be interesting. As sibling top-level comment points out, humidity is a consideration if you're going to go all emo with that loose-fitting black hoody.
I am not convinced by any answers. They are predictions--that's great for talking and might make a good road trip argument.
But I think this really has to be tested. Someone call the MythBusters back.
Wouldn‘t clothes made from aluminum foil or another mirror like substance even be better than white clothes in the summer?