Tolls on interstate infrastructure have also traditionally been looked down upon. Charging people to move themselves or goods across state lines, even where arguably constitutional, rubs Americans the wrong way. Easing interstate commerce is a large part of why the federal government exists.
Perhaps the solution is for the river shipping industry to form a co-op to build, own and operate the necessary infrastructure.
So it is no surprise that this infrastructure - built in very different political circumstances to today - is not going to be maintained. When you look at all of it - infrastructure, America - none of it is going to be maintained when the oil runs out. Suburbia with those nice big highways wasn't ever going to be viable post oil. Hopefully Tesla can make U.S. suburbia viable.
What baffles me is the total dismissal of a private infratructure project which charges tolls. This would seem to be a perfect project for user-pays funding: the project offers a service with a specific, discrete in time and place, easily calculated value which is extremely large to the user who are supposedly suffering severely under the status quo. My only guess is that the lobbyist affiliation here is the whole story: the industries think they can get full taxpayer subsidies for the costs without having to pay much or any of it, and it's worth waiting for a government solution.