According to a Washington Times editorial, the Congressional Budget Office is claiming road users should pay more because of externalities, but it claims that the lack of funds for roads are not due to a lack of funds, but because of funds diverted into “mass-transit programs and grants to local police departments to run speed traps”. The CBO supports VMT (Vehicle mileage tax) because of the need to protect revenue.
In other words, it is a bit of a rant. The hint of truth is that, yes funds are diverted to other purposes, and legitimate arguments can be made about that.
However, the best argument for VMT is not revenue protection. For there can always be multiple ways of addressing that (although none of the others are particularly good), it is that VMT can far more effectively address congestion and be the platform to treat roads as an economic good and a service with revenue linked to investment, rather than a public good funded from politiclaly driven taxes.
While it is easy to get angry about the misuse of funds, the answer is not to oppose more efficient road pricing, but to support better governance mechanisms for the use of the revenue collected.