To understand what’s going on, it may be helpful to start with what we should be doing. The federal government can indeed borrow very cheaply; meanwhile, we really need to spend money on everything from sewage treatment to transit. The indicated course of action, then, is simple: borrow at those low, low rates, and use the funds raised to fix what needs fixing.

But that’s not what the Trump team is proposing. Instead, it’s calling for huge tax credits: billions of dollars in checks written to private companies that invest in approved projects, which they would end up owning. For example, imagine a private consortium building a toll road for $1 billion. Under the Trump plan, the consortium might borrow $800 million while putting up $200 million in equity — but it would get a tax credit of 82 percent of that sum, so that its actual outlays would only be $36 million. And any future revenue from tolls would go to the people who put up that $36 million.

There are three questions you should immediately ask.

First, why do it this way? Why not just have the government do the spending, the way it did when, for example, we built the Interstate Highway System? It’s not as if the feds are having trouble borrowing. And while involving private investors may create less upfront government debt than a more straightforward scheme, the eventual burden on taxpayers will be every bit as high if not higher.

Second, how is this scheme supposed to deal with infrastructure needs that can’t be turned into profit centers? Our top priorities should include things like repairing levees and cleaning up hazardous waste; where’s the revenue stream? Maybe the government can promise to pay fees in perpetuity, in effect “renting” the repaired levee or waterworks — but that makes it even clearer that we’re basically engaged in a gratuitous handout to select investors.