The problem with the space shuttle example is that it has incredibly limited scope. Yes, we could build a large program to exacting specifications, but once they change, all bets are off. The space shuttle software doesn't need to adapt over time.
And you're right, it is incredibly expensive... but even in my example, that just moves us forward to the Roman Empire, or something. People know how to build an aquaduct, but only the most excessive society on the face of the planet can afford it.
But if we're sticking with the civil engineering analogy, a road is not built in 1-week sprints with the route potentially changing as requests come in that it link more or different towns. So you have to compare like with like.
And you're right, it is incredibly expensive... but even in my example, that just moves us forward to the Roman Empire, or something. People know how to build an aquaduct, but only the most excessive society on the face of the planet can afford it.