Most vehicles involved in chases are stolen. Those that aren't generally have removed or stolen plates.
In other words, reading the plates is the current practice, but usually yields little useful intel.
There are plenty of problems with policing in America (and worldwide, for that matter), but this ignores the entire category of "crimes involving stolen vehicles."
If they can ditch the car then they're gonna be ditching the GPS dart with it.
Knowing where and when they ditched the car is still a massive advantage.