"I don't drive, why should I pay for roads?" - oh wait this is real, roads are maintained by gas tax.
Knowing that UK fuel duties[1] are not at all hypothecated (nor 'Road Tax', which is actually a vehicle excise duty, and goes in to the general tax pot anyway), I wanted to check this. It looks like the low, low fuel tax in the US isn't dedicated to roads. Some revenue goes out, some other revenue goes in, but the consensus is clear that there's not actually enough in various vehicle-based taxations and charges to support the actual infrastructure expenditure (which it seems is also woefully insufficient). But maybe that's not a problem in every state. My quick browse didn't reveal enough detail.
(Even hypothecated/'ringfenced' taxation is a bit of a fudge. If you try to say "this lot of dollars came in for roads so we'll spend them on roads, that lot came in for schools so we'll spend them on schools" you still end up with 'unpreallocated' dollars being distributed to things both already allocated-to and not allocated-to, but because you've already said this labelled chunk of change goes straight to that chunk of spending you'll not like to add as much spare-change there to make labelled+spare equal what you might have done if given a free hand with utterly uncommited funds (with every other possible commitment vying for at least as much attention as before). It'll depend highly upon special-interest pleading, but that already got them those 'dedicated pot' allocations and other pleading for unguaranteed moneysinks are going to try even harder to take ad much of the rest as they can.)
[1] £0.5795 per litre. Not including VAT ('sales tax') of 20%. (VAT adds about £4bn to the £27bn of basic hydrocarbon duty collected.) If I've worked in the right values in the right way, this equates to US$2.98ish per US Gallon, compared to rough Federal+State fuel taxes apparently being US$0.5264 per USG, prior to any other liabilities I don't know how to account for.
[2] For reference a whole cost of fuel is havering around 142.9 pence per litre over here, which seems to be $7.36/USG. Checking current Hawaiian prices, which I've found to be amongst the highest in the US in past forays, they're currently at $4.316ish.