"Pay for what you use" in the case of roads would be the incremental amount of road damage caused by each vehicle, rather than the total road cost divided by the number of vehicles.
The large majority of road maintenance costs are attributable to weather and semi trucks. (Road damage from vehicles is the fourth power of vehicle weight, so one semi does as much damage as thousands of cars.)
Moreover, the problem with allocating the fixed cost (weather) portion of road maintenance to cars, or the cost attributable to large trucks, is then you over-deter use of the road. You don't want an inefficiency where you deter someone from using the road even though they value their use of it more than the cost to the state of allowing them to, because then you waste idle road capacity for which the fixed construction costs must be paid either way. Doing that also requires the amount of the toll to be even higher, because then you have to amortize the fixed costs over fewer vehicles. You end up with tolls much higher than the efficient level per vehicle even if the tolls do only pay for road maintenance, because of the over-deterrence.
The better solution is to pay the fixed cost portion from general taxes and only charge the marginal cost for usage.
But if you charge only the marginal cost for "light" passenger vehicles then the amount is so small as to not even be worth collecting.
The large majority of road maintenance costs are attributable to weather and semi trucks. (Road damage from vehicles is the fourth power of vehicle weight, so one semi does as much damage as thousands of cars.)
Moreover, the problem with allocating the fixed cost (weather) portion of road maintenance to cars, or the cost attributable to large trucks, is then you over-deter use of the road. You don't want an inefficiency where you deter someone from using the road even though they value their use of it more than the cost to the state of allowing them to, because then you waste idle road capacity for which the fixed construction costs must be paid either way. Doing that also requires the amount of the toll to be even higher, because then you have to amortize the fixed costs over fewer vehicles. You end up with tolls much higher than the efficient level per vehicle even if the tolls do only pay for road maintenance, because of the over-deterrence.
The better solution is to pay the fixed cost portion from general taxes and only charge the marginal cost for usage.
But if you charge only the marginal cost for "light" passenger vehicles then the amount is so small as to not even be worth collecting.