Uh, because if you wanna talk about the radii of the spherical shells like that, you need to consider the actual radii, namely the distance from the shell to th

Uh, because if you wanna talk about the radii of the spherical shells like that, you need to consider the actual radii, namely the distance from the shell to the center of the Earth. In your example (which is an exaggeration, FL600 isn't really used for commercial flights), airspace goes from 0 to 18 km above the surface of the Earth. The Earth's radius itself is approximately 6400 km. So airspace is the shell between 6400 km and 6418 km. Starlink operates around 6950 km. That's not "an order of magnitude more", it's completely comparable to airspace, so the space available to the satellites scales with the shell's thickness in almost the same way as airspace does.