Currently all the tax revenue that the federal government raises goes directly into the general fund. Congress then allocates funds from this huge pool of money to all of its many programs. This means there is no connection between how money is raised and how that money is spent. And no guarantee that the money raised for a specific purpose is spent on that purpose.
We as a nation raised trillions of dollars in tax revenues from the taxes on gas at the pump, but very little of that money was spent to maintain the roads and bridges of this country for decades.
The money raised was not spend on roads. Changing gears a little bit, can you imagine if the Post Office was ran like road construction in the USA? Congress would raise money with a tax on everyone, on the off chance that you might want to someday mail several thousand pieces of mail. Then that money could be put into the general fund to be spent on anything the politician wanted to spend that money. Later when you wanted to mail a letter for free it would be thrown on top of the pile of letters that there was no money to ship.
For the most part, I see the Post Office as a governmental system that works. It has its own budget and it raises money to cover its own running costs from the people who use the service. Nobody is forced to use the Post Office. The only monopoly given to the Post Office is for first class mail delivery, but it came with the requirement that the Post Office deliver mail to everyone in the USA, no matter how remote they live.
We could set up a similar system for America’s roads and bridges. An independent federal agency that just polices 50 separate independent state programs would ensure that the money raised by taxes on fuel are used to fund road and bridge construction and maintenance. And fuel costs are a very good way to apply a usage tax on vehicles. The heavier a vehicle is, the more fuel it uses to move down the road. Such a system could totally eliminate the need for toll roads or bridges. You pay your toll when you pay for gas.
This same design should be used for all the important tasks we need our government to reliably accomplish. Health care insurance, retirement insurance , and air safety are all too important to leave to all too human politicians. Each of these areas could be spun out of the general fund into independent agencies.
Agencies funded by the people who use the service would ensure that the money raised would be spent on the services required by those customers. This would reduce corruption and reduce expenses. This would give us the level of government we want, make that service be offered with good customer service, have a level of review that ensures a check and balance, and reduce costs.