It is almost always incorrect and counterproductive to speak about "THE" problem, since there is rarely a single problem of which to speak, or even a single cause that represents the majority of the problem. In this case, there are at least a few "problems" we can discuss, and dismissing any one of them as "not the problem" is simply wrong.
The first set of problems or challenges involves creating new infrastructure where required, maintaining the existing infrastructure, keeping it clean and usable, creating and maintaining signals and signs, and so on. Those are not being addressed well enough in the USA, and the infrastructure has decayed to a critical condition where restorative maintenance is vital. The second set of issues revolve around traffic and congestion management, and the third set are about raising the funds required to pay for all this. I may have missed some, too.
Please note that every single one of those problems is an essential part of the system. None of them can be ignored: any single issue, if left to rot, is enough to ruin the system. And they ALL have both economic and political components in both the problem and the solution.
"Everything should be made as simple as possible... but not simpler than that." --Albert Einstein
