I'm assuming there that any such system would be appropriately tuned not to alert outside of a reasonably safe window. My assumption is that it would promptly notice the conflict following any communication which under ordinary circumstances should leave plenty of time to correct. To be fair I don't expect such a system would address what happened in this case because as you note false alarms on too short a notice pose their own danger which may well prove worse on the whole.

This specific situation I think could instead have been cheaply and easily avoided if the ground vehicle had been carrying a GPS enabled appliance that ingested ADS-B data and displayed for the driver any predicted trajectories in the vicinity that were near the ground. Basically a panel in the vehicle showing where any nearby ADS-B equipped planes were expected to be within the next 30 seconds or so.

> stopping at a red light unnecessarily

Is it not always legally necessary where you live? It certainly is here. When I described them as unnecessary I was recalling situations that would clearly be better served by a flashing yellow.