It may have also been a class/cultural thing. A man on horseback is actively riding the horse, a man in a 2+ person chariot is having someone else do the hard work.
yes, I know the stories of the amazing accuracy of horseback archers (mongol, native american, ...). Just saying that the 2-man thing may be more efficient than you give it credit for.
If you don't have chariots and they do, just fight where the chariots can't.
Kind of like how George Lucas made the empire look like the Nazis so you know who's good and who's bad in the first minute before you even know what else is going on or how in most artwork about the American revolution it's obvious which side is and isn't a professional army.
True. But wasn't the reality complicated (as usual)? There were French regulars on the American side and various militias fighting on the British side. And Indians fighting on both sides.
Yes.
Which further underlies the point that you shouldn't take the artistic depiction too literally.