Grayscale AA is still common on Retina screens, but subpixel AA is rare. Mostly because subpixel AA is difficult to do compositing with transparency with, but a

Grayscale AA is still common on Retina screens, but subpixel AA is rare. Mostly because subpixel AA is difficult to do compositing with transparency with, but also because it's less necessary on Retina screens. The tradeoffs are just to the point that it's not considered worth it.