>> Software routinely solves database coordination problems with millions of users per second.

A naive view that confuses the map with the territory.

While in a database state you write a row and reality updates atomically....for aircraft they exist in a physical world where your model lives with lag, noise, and lossy sensors, and that world keeps moving whether your software is watching or not. Failed database transactions roll back, a landing clearance issued against stale state does not. The hard problem in ATC is not coordination logic but physical objects with momentum, human agency, and failure modes that do not respect your consistency model.