The problem many mostly rural states have is the number of miles of roads versus a relatively small population - miles of roads per capita.
But that does not explain all of Oregon’s highways money problem. You need to only compare Oregon and Montana.
Montana has a population (1.4 million) about 1/3 of Oregon’s (4.27 million).
Montana has about 14,000 miles of highways (12,900 state, 1,191 interstate). It has a state gas tax of $0.33 a gallon.
Oregon has a bigger population and fewer miles of highways (about 8,1000 - 730 Interstate and 7,400 state), yet its gas tax is already $0.40 a gallon ($0.07 more than Montana).
I stated out thinking the largely rural relatively small population of Oregon, and not tiny land size (larger than 51 other states) was the problem. But obviously the larger state of Montana with a smaller population than Oregon does not need a gas tax as much as what Oregon already has.
Conclusion: Oregon is mismanaged in every way.
One possible caveat: County roads maintained by the counties and the portion of state gas taxes that goes to that. But alas, I looked it up, and Montana has nearly twice the miles in county roads as Oregon while both designate some of the state gas tax to pay for them.
Not only is it higher but with the much larger population, they are selling far more gas and getting much more money.