My concern is that municipalities have successfully put the burden of risk on private companies when it comes to infrastructure procurement, so that if a project goes over budget, the private company has to pay that overrun, which I think is fair. They're the ones that are responsible for the mistake.
I worry about loan guarantees that actually protect the private company against its own failures at the expense of taxpayers. I don't have a problem with infrastructure companies making a profit, but profit and risk go together. If they make a mistake, it shouldn't be my constituents who pay for their mistake. That's my principal objection to its use in infrastructure procurement.