Oh, I dare say that if someone in an official capacity - or even someone not in such - wish to track you, it’s kind of easy. Do you use a cellphone? Do you usually take it apart and rip out the simcard and the batteries? That’s what you have to do, you know, to not be a live beacon.
And if we’re talking tech - even 40 year old tech - does the word “box” ring any bells with you?
The point wasn’t that they knew where he was, but that they knew where he was going. They would have to know his route in order to place a stationary gunman on the roadside, for him to pass by.