Fairly straightforward actually. Up until recently, not one of the Glock airsoft pistols manufactured was licensed by Glock (who has both image and logo copyrights on all their firearms). Palco/Spartan Imports secured the North American rights to distribute a Glock airsoft pistol recently, and now, with Glock, are enforcing that copyright infringement.
The Tier One Tactical Operator
Tippmann Arms M4A1
KWA USP .45, KJW P226, KJW hi-cappa