I walked into an Apple Authorized reseller. Apparently their MBP Retinas still have Mavericks. I would have expected all models to have Yosemite by now...
I am based in Asia by the way. I don't know if location even matters.
Solely depends on the date computer was manufactured. Same hardware just upgrade, my own 13" 2.8 Retina came originally with Mavericks, less than two months ago I just upgraded out the box. Same am based in Asia.