because thats what colour behr made the originals - have a general look say take 100 cars of varying makes and models - you will find its a 50/50 mix of black/silver finishes

e.g manufacturers use subcontractors to make there parts so whats availabe gets used ! - bu also do you think the likes of radtec/pace/pro-alloy would all be in business if all the parts had to be black ? and they had been producing silver finished products - it makes fook all differance