Canon states they are colored this way to keep the flourite based elements from overheating in hot environments. So does this mean they perform better than Nikon, Sigma, et. al.? Or have the other vendors solved this "issue?" NASA even uses Nikon!!
"So does this mean they perform better than Nikon, Sigma, et. al.?"
Yes it does!
Otherwise it would be stupid to spend thousands of dollars of my money on Canon brand lenses. I, and you, are free to buy whatever. Canon has the best lens lineup in the world. Not even close.
"NASA did not grind that glass......Perkin-Elmer did. And they trustedthe subcontractor to do it correctly."
That's a cop out and not an excuse for sending a billions, that's billions with a b, of dollars gadget into space. And not their only screw up.
"Lets see how Webb performs."
I can image they will scrutinize it with a fine, very fine, tooth comb many upon many times. But it's NASA so who knows.
My understanding is that as well as the coatings issue directly, a significant factor is that the white lenses are all metal, and in extremes of temperature they can expand/contract and thus impact the optics of the lens. This makes them extremely robust, but heavy. By making them white to reduce heat absorption and thus reduce expansion and contraction. Sony also make some metal lenses I believe, so I guess they are doing the same thing. Nikon have gone for engineered plastics that are less inclined to this thermal variation, so they don't need the white.