Why is "no tax funding" a hard requirement? I would think the lowest cost to get that market information publicly shared and forthcoming (and thus increasing the efficiency and effectiveness of the market), would be for a government dept to operate the frontend distribution, but require regulatory submissions of transaction data within reasonable latency windows. It's just a modern form of say US SEC document submissions and EDGAR to distribute.

I don't see why you can't do that?

There's plenty of things that cost money that legislation forces companies to do anyway, regardless of if there is a 'funding source' or not.

Although this particular one is from the FCA so presumably is taxpayer funded anyway.