Since we're talking about a hypothetical solution, in theory this would have a spec and potentially even be further centralized. I could imagine a world where

Since we're talking about a hypothetical solution, in theory this would have a spec and potentially even be further centralized. I could imagine a world where the IRS ran the tax software for every taxing entity in the US. Each jurisdiction would have to configure their specs or potentially even codify the business logic. International would likely be tricky but it's similar to what is being done with ACH and other banking systems that are slowing moving to international. So, it's not impossible there's just not much of a push for it.