This wouldn’t be truely democratic. It would rather be just like donations. Government spending works, because it’s all out into the same basket. If it weren’t, then rich taxpayers would move the movey to projects they want - and as would have very little old-age welfare, because they don’t pay much taxes anymk6and every group in society would put the money into their projects.
in Australia, when we pay taxes, we get a receipt. The receipt shows what our taxes were spent on (lemmy.world)
I assume “Other purposes” is govt kickbacks to mining and gas companies 😬