Phase information is already used by precise GPS receivers. The electronic components and software are probably much cheaper than wires in the ground everywhere

Phase information is already used by precise GPS receivers. The electronic components and software are probably much cheaper than wires in the ground everywhere. Also, the guy did say they have centimeter precision, not sub-mm. cm is the wavelength of microwaves. The nano referred to nanosecond timing, which is common in every computer these days. These kinds of suggestions of using a simple mechanical solution instead of a sophisticated one often come up when high tech machines are discussed. Driverless cars should use wires in the road, or communicate with each other using radio instead of vision, SpaceX booster landings should use towers and wires to guide it the final few meters, walking robots should use wheels, Boston dynamics' Handle robot should be a conventional 4-wheeled vehicle with a robot arm on it, aerodynamically unstable aircraft that depend on computer control should not be made, etc. I think people have a bias that says "Tasks I could imagine doing myself are cheap and tasks where I'd be out of my depth even knowing if they're possible are expensive.". But really, hardware is expensive and software and electronics are cheap, at least by unit costs.