True the MacBookPro retina has screen of pixels of 1920X1200 but the screen shots I take are 3840X2400. I believe what goes on is the screenshot does not come from what is displayed on the desktop but by what is streamed/recorded at the chip level. Not sure how this takes place but here's a shot, 3840x2400 (4K) unedited direct from Ultraflix. I only opened in Photoshop to add logo and save as .jpg (ihang doesn't accept .png Mac's native screenshot format.)


And for your viewing pleasure below is the AMZN same shot of Rampart streamed in 2K, but again the screenshot file is 3840X2400 (4K)