The US already provides publicly accessible conjunction avoidance data based on data points they have. They don't have the same number of satellites in the sky to make real time observations in as many different directions though.

> so, these systems should have existed for decades now.

Dubious. Perhaps if Congress could be persuaded to invest in tons of radio telescopes / radars, positioned all around the world, but good luck with that. The space-based approach used by SpaceX is something that presently only SpaceX is equipped to implement. Tracking star conjunctions only gives you high quality data on space debris / satellite maneuvers if you have a huge net of star trackers in orbit, and that's something which only SpaceX has been able to do.