When the government buys a piece of steel, a chunk of that is property taxes of the owner of the factory building, a huge chunk of that is business taxes, a huge chunk of that is income taxes of the workers that work there.
If the government can own that infrastructure as a fully nonprofit entity that pays zero taxes, the government can buy the steel for $50 instead of $100. That means our income taxes can also be much lower, because the government can be more efficient.
Right now a huge chunk of the taxes you pay to the government go toward paying second-order taxes.