AFAIK The radar is tuned to explicitly ignore non-moving objects because it has to be able to ignore overhead road signs and other such stuff[1]. It is more tuned to changes in speed of the vehicles in front of the car.
Tesla was working with their supplier (Bosch?) to get the radar to work as a six-field array, providing more resolution than “the nearest return is 100m away”. The discussion at the time was tht higher resolution radar would remove the last advantages that lidar supposedly has over cameras.
[1]: https://www.tesla.com/blog/upgrading-autopilot-seeing-world-...