> I think arguments like that ignore the interconnectivity of complex national systems (e.g.) a London business whose customers and suppliers are based around the country.

And indeed employees. I'm based in Cheshire (home worker), we have offices in most cities and large towns across the country (and indeed globally). How much of my income tax is counted towards 'rural northwest' and how much to 'London' where the HQ is. How much of the profit I generate gets allocated to London.