But with interstellar travel for centuries and 3000+ years of scientific progress, we can't manage to keep an eye on the immediate environment of an inhabited planet?
Just some thoughts:
Real life Earth has different countries putting all kinds of things in orbit.
In the Charted Space setting, worlds with...
Low to mid tech level.
Low to mid population.
Small to mid industrial base.
Small to mid tax base.
Environmental issues that make air and aerospace travel not the best option, like insidious atmospheres, high winds, or relatively close settlements connected by high speed rail.
No specific need for aerospace research and development.
A unified world government or no military necessity for space assets.
Little interest in space science, since they can get the research from other worlds.
Not enough trade to require a highport.
...wouldn't have much in orbit.
What would a world without those disadvantages need or probably have?
Communications satellite network.
Weather observation satellite network.
GPS satellite network.
One robust satellite network could probably handle all of these requirements.
Deep space tracking / early warning satellites.
Traffic control satellites.
Probably a highport.
A military highport / drydock / shipyard.
Military assets like system defense boats, monitors, planetary navy vessels, customs vessels and orbital defense platforms and associated tracking satellites.