Why is the MacBook keyboard black instead of grey?

Question

A curious question about industrial design.
When Apple released the unibody MacBook, why has the keyboard been changed to black instead of the original silver color from the older MacBook Pro models?
I personally prefer grey keys a lot more than black keys as they blend in well with the aluminum body. Grey, like black, doesn't get dirty over long periods of use.
Some argue that the contrast lets a user recognize the black keyboard better. My counter argument is that the silver keyboard on the old MacBook Pros did not trouble users. Since the hands are already rested in position during typing, users don't need to look at a physical keyboard as often as a touchscreen keyboard.
Others argue that it's to distinguish the keyboard from the body. If that's the case, then why is the trackpad silver instead of black?

Answer 1

A silver keycap with a white letter does not provide sufficent contrast as legislated.  A silver keycap and a sufifciently contrasting letter color would be very difficult to illuminate.  The current ID solution provides sufficient contrast, and the ability to illuminate the letter.
"Do you have any sources that describe the standard?"
I believe the inital legislation was passed by the EU, and it was part of ergo standards, including usability by the physically limited.