GPS receivers are ubiquitous in many ground-based applications, from large-scale industrial transport navigation systems to fitness trackers and smartphones. However, using GPS receivers in space is a much more challenging task compared to normal terrestrial use. Here is an overview of some of them that work in space!

TL;DR: There's a limit imposed by ITAR - because what flies at 60k+ ft, 1k+ knots and would really benefit from a GPS? Missiles.