I've bought two MBPs in recent years: in December 2011, and again in August 2015. The first time around you could definitely get the matte screen, although unfortunately only with an ugly grey bezel. Not so sure about 2015 though.
It does exist-- from hobbyist entrepreneurs. 51nb has been selling motherboard upgrades for the old 4:3 ThinkPad models for a few years now, and others have begun to specialize in whole-system integration, additional mods, and complete systems based on this work (I'm one of those people, though I also do it as a hobby).
My three ThinkPads X60s machines are all Broadwells, with nice 12.1" 4:3 high res screens using modern backlights I fabricate myself. They work so well I intend to build more.
Well, there is the problem. If monitors and notebooks are sold with 16:9 only, then of course there is no "demand" for 4:3, because you don't sell any! This argumentation is scewed.
Matte screens are a crutch. I’m a big boy I can figure out how to properly light my office. I don’t want to stare at my text through cheese cloth for the sake of those who can’t.
In my experience this is controlled by shutting the blinds over the windows so the naughty sun doesn't make the laptop screen impossible to use. Great, no more sun in the cubicle farm. Thanks guys. :-(
Reflective screens are the biggest shame. They’re worse but they sell better. For a while 4:3 looked “old fashioned.”
Turns out that a tall form factor works for phones, but thankfully most manufactutors relize that tablets should be 4:3 or close to it.