Aviation and Space has a lot of challenges, but also a lot of flexibility.

Planes, for example, can share the same geographic location -- just at different altitudes; e.g. 25000 ft vs 33000 ft vs 45000 ft., etc. After a certain altitude there isn't anything. No clouds, no birds, just air; set your auto-pilot and go. Takeoff and Landing can be hairy, and you gotta worry about mountains, but that's about it. A basic radar makes it easy to see, and not hard to broadcast by radio.

Same basic idea for space. Gotta get out of orbit and not get cooked by radiation, but otherwise there is a whole lotta empty, and it's not hard to see what's going on with things like radar.

On the ground it ain't so simple. Someone stuck on a rail, avalances, bridge collapses, hills vs inclines, snow / ice / rain / high-winds, and no ability to multiplex, so scheduling gets even harder since there are only so many ways into or out of a location. Trains full of high explosives or toxic chems drive right through downtown areas, often multiple times a day. From a crime and security perspective, airports are locked down pretty hard, while most people could probably just drive to a siding near them and fuck around; you can derail a train with a $400 block of steel you can order online. Communication and signal loss is also way more complicated, esp. if you're going through a mountainous or remote area.