I would argue that 8% is absolutely negligible; however one thing that isn't is that airspace is a narrow band vertically (12 km? Not sure exactly), while LEO is about 800 km thick (from about 200 km, because the Kármán line isn't good enough, to about 1000 km).

Conversely:

> Daily flights 50k-100k. Total number of satellites <20k.

Those 20k satellites orbit roughly every 95 minutes, so they're doing ~15 orbits per day, and even the longest flights from conventional aircraft are about half that distance, so by distance each satellite in LEO is doing strictly more than the equivalent of 30 flights per day each.

Research I'm doing for a blog post has shown me that the exact position of a satellite is surprisingly variable compared to what you'd reasonably expect from a "Newtonian spherical Earth with a perfect vacuum" approximation of the orbits, enough so that it makes sense to treat 1 km as the "collision avoidance manoeuvres needed" threshold.