RF tracking would be better if you don't have access to a location with line-of-sight to the passing traffic. Also cheaper than OCR-ing camera footage, and can track vehicles going in both directions, trucks towing trailers, cars with no front plate, etc.

Plate tracking is better for determining direction, and is probably more reliable because TPMS aren't constantly transmitting. You could miss a car if it doesn't have any TPMS info transmitting while it passes your station.

Is phone tracking still possible for the latest iOS or Android phones? I thought my BLE and MAC addresses are randomized, but I don't know much about this beyond that headline. I'm guessing a Stingray type device would still work though.

There are definitely many better ways of doing this, it’s more of a thought experiment.