the strap line of the article was that to design a robust system it will have to be "paid for use".

The Ordnance Survey in the UK sell access to their system where sophisticated surveying receivers spend 30 minutes in contact over mobile phone networks to OS stations that have their grid reference known to a fraction of a millimetre.

The software knows from the average variation what the error is from the satellites signals, and makes correction to within 1 mm. Satellites values, at the metre resolution, move about a lot, I see it on my (non-phone) phone.

I bumped into a surveying set-up recently using a Bench Mark that I had photographed and after a time they gave me the OSGR to the mm. Which I used for Stonehouse Ocean Bridge SO 7981 0504

I can't help thinking that a system accurate enough for car navigation could be bolted onto mobile phone masts. Let's face it, we pay for access and the masts don't exactly move. It has been tried in an informal way. It just needs refining. Of course in big cities with tall buildings it may not work so well. Like Lundun (innit?). But would us yokels care? Though beware 5G, that may be easier to use such a system at this stage.