[AnthonyMouse]

Engineers have no trouble crafting a solution that fits within a given budget.

The real problem, with all of it, is surplus. What happens to the resources you didn't actually have to spend, once an efficient solution has been engineered?

If you let engineers decide, they spend it on over-engineering. If you can do it for ten million but there is a billion dollars in the budget, you can also do it for a billion dollars and then square away lots of implausible edge cases and improve materials efficiency by a sliver etc. But this is wasteful because those things have diminishing returns or a poor cost/benefit ratio and you ended up spending a hundred times more than was necessary for a couple of percent improvement in the result.

If you let politicians decide, they spend it on cronies. This is wasteful, because obviously.

What you have do is to figure out how to make the surplus end up back in the hands of the taxpayer without letting any of these resource parasites get their hands on it.