Well, yes and no.

It’s a bit of a myth that government spends tax revenues. Actually, it just spends money into existence. Taxation exists to give currency its value within a territory ruled by a government. Once a tax obligation exists denominated in a currency, the government can use that currency to buy the goods and services it needs to provision itself. Tax also serves to act as a brake on inflation, as well as to effect social policies, such as inheritance tax preventing the emergence of a permanent aristocracy, and to reinforce the feelings of connection to a government’s policies that incentivise democratic participation.

But if you think about it, government prints all the money in the first place. It doesn’t need to tax it first. It creates it when it spends. The only practical limit is the risk of excessive inflation. And the political limits of tolerance for public debt levels.

As for the value of public goods, well that can partly be measured by the level of increased economic activity it stimulates, and partly by the political popularity of a project.