This sounds to me like the "invoice problem", or whatever you might call it. Consider business invoices. Tens of thousands of entities have to share the same

This sounds to me like the "invoice problem", or whatever you might call it. Consider business invoices. Tens of thousands of entities have to share the same general flavor of data, and each already has a system for doing it. They all have to receive and process that data regularly, and have their own systems, charts of account, item names, etc. Harmonizing all that is very difficult. The IRS offers standard forms but there is often more than one way to select them or fill them out. For example, on an 1120S, the accountant might place an expense in one of the standard categories or in a table of other expenses. But even more difficult, every user might have different ways of categorizing their income and expenses, and the people sending them forms might do it one way or another. Such a service would have to be opinionated and convince each reporting entity to adopt the system in place of the home-built one they're already using.