Some problems can’t be solved, like choosing the UK entry for the Eurovision Song Contest. It doesn’t matter whether you use a panel of experts, a public vote, or some combination of the two. You will still wind up with a “Cry Baby” (last place, 2003) more often than a “Boom Bang-a-Bang” (tied for first place 1969).
It’s the same with HMRC: whether you let HMRC, the Treasury and politicians decide or run proposals through a consultative process, you will never pitch the tax authority’s powers at a level that pleases everyone.
The best you can hope for is to avoid “nul” points.