That’s a different problem. Regular radar is setup to detect flying aircraft and is very useful to avoid flying into mountains, avoid mid air collisions, etc and it’s not what we’re talking about. That type of Radar has proven necessary on many occasions.

Spending a great deal of money to track aircraft on the ground however is only helpful when one of the aircraft is on the ground. It’s only partially useful when visibility is low, at which point air traffic control can be especially paranoid.