I find myself wondering what the cost of a low-power ground radar

I don't see anything being necessary.
Accidents will happen in the future and they will always happen if
humans are involved. There is nothing that assures perfect safety.

Maybe a moving map display might prevent an accident like this. However,
there will be another accident that is caused (also) by a malfunctioning
moving map because it was not aligned correctly or an old version or a
bad scan...

Living is always life endangering.

As long as far more people die because of cars and guns we better should
take care of that!