The way the high resolutions work is that the screen is rendered at 2x then scaled down to fit the display. This does lose a bit of that subpixel antialiasing, so you're right that it doesn't appear quite as crisp as the native retina scaling. Hopefully this is something they're working on - Quartz could theoretically be modified to detect the scaling factor for the display and render text, shapes, etc to match the native pixels.