1. Tolls that are implemented today are never predicated on the assertion that they will end. People in charge of building and maintaining infrastructure know well that the infrastructure is never "paid for" but in fact requires a constant revenue stream for ongoing maintenance and major rehabilitation work. A perfect example of this is the George Washington Bridge, which carries I-95 across the Hudson River between New Jersey and New York City. It probably had a design life of 50-60 years when it was built, but it is now more than 80 years old and as sturdy as ever because of ongoing maintenance and rehab work.
2. The big attraction of tolls (as opposed to a fuel tax) is that it generates revenue that isn't just tied to highway users in general, but is paid by users of specific roads and bridges. This pushes revenue generation one step closer to a true "user pays" system, which is the fairest and most equitable means of financing infrastructure of all.
3. Another attraction of tolls is that they are entirely discretionary for the users. If you don't want to pay the toll, then don't use that particular highway or bridge. Motorists make decisions like this all over the country these days, and it seems to work just fine.
In my state GA 400 Toll road WAS predicated on ending after paid for.
Secondly, your definition of “user pays” neglects these users already PAY taxes for roads (supposedly) that does not get used for roads, very often.
Lastly, discretion. You can live with it, but I don’t want to. I want my roads free, because I and many many others already pay for them. Make the departments that get the tax money for roads use it for roads, not propose tolls.
Government is always looking to score more money to use for things they already should be doing with the money they have. SPLOSTs are perhaps the worst deceit perpetrated on the taxpayer. It’s always an appeal to “make the other guy pay” nerve once asking government what the hell they did with the money in the first place.