UPDATE: From a reader/Design Manager who knows a thing or two about mass manufacturing, white equipment may indeed be harder to produce than black:
"The process to make the back of the glass black is an electroplating process. This creates a very durable consistent and smooth black finish. To make white on the other hand you have to paint the back of the glass with white paint. It is difficult to create a smooth opaque look with the white. Also if the white paint goes on too thick it is difficult to glue the glass on because the glue will stick to the paint, but the paint will pull off of the glass. "