This may be due to the GCA '68 import points calculus. Glock would have to build them in the USA since a gun that small probably couldn't rack up enough import points, I'd expect (same reason the .380 Glocks aren't importable into the U.S.). The G26 and G27 barely make it in as it is.
I had thought of that, however the G26 and G27 already have additional features for getting import "points" due to their small size. It's why the sub-compacts have those tiny shallow thumb-rests on the sides of the grip-frame. IIRC, Glock also installs inexpensive plastic adjustable sights that are removed stateside for the fixed ones for more '68 GCA import points on some models...
They're both "Target and sporting features", and makes th G26 & 27 importable.
Here's the point system under the GCA as I understand it to be, and a pistol must have 75 points to be importable, Glock loses the biggest on the metal alloy frame requirments which were all designed to stop inexpensive European "Saturday Night Specials".
Characteristic Points
Length: for each 1/4" over 6" 1
Forged steel frame 15
Forged HTS alloy frame 20
Unloaded weight w/mag (per oz.) 1
.22 short and .25 auto 0
.22 LR and 7.65mm to .380 auto 3
9mm parabellum and over 10
Locked breech mechanism 5
Loaded chamber indicator 5
Grip safety 3
Magazine safety 5
Firing pin block or lock 10
External hammer 2
Double action 10
Drift adjustable target sight 5
Click adjustable target sight 10
Target grips 5
Target trigger 2
Worst case senario, they manufacture just enough stateside to be legal under US import regs. Plenty of smaller mfg's with less cash or market presences as Glock manage to do it, and they already have the Smyrna GA facility to work with.
The main place a single-stack Glock compact would lose points as compared to the G26 & 27 would be on the weight. It would probably gain a few points as the grip might be a bit longer to accomodate an extra round or two in single-stack format. Since most of the carry market's gripe with the 26 & 27 is the width, making it a bit heavier wouldn't be a huge drawback. Or, they could "Pull a Tarus" and just like Tarus ships all their small revolvers with long barrels, then ships them right back to Brazil, Glock could use heavy metal magazines, and just switch them with polymer ones stateside.
Personaly, I think Glock hasn't come out with single-stack sub compacts in anything other than .45 and .45 GAP because they're doing well enough and just don't care.
And to some above posters, I too would love to see what KT's take on the .22 LR in both a pistol and a rifle would be. I think something that folded down to the size of the M6 Scout, but was a magazine fed semi-auto would have lots of appeal. I can't imagine that the M6, the Marlin Papoose, or the AR7 are the pinnacle of the take-down .22 LR.