Think of it this way: the Earth's radius is ~6400km. Starlink orbits less than 10% higher than that.

Depending on the thickness of the orbital shell there might be significantly more vertical space available, but the surface area isn't much bigger at all. (It's actually only ~18% larger[1].)

[1]: https://www.wolframalpha.com/input/?i=%284%CF%80%28radius+of...