There are exceptions. The Dallas-Fort Worth tollway (now I-30) eventually became free once the bonds were paid off, after a fight over extending the tolls, if I remember correctly. Kentucky’s system of parkways (parts of which are now I-69) were once tolled, but are now free. The last ones became free just a few years ago.
You remember it correctly. But the fight was extensive and the state had to threaten the DFW toll authority with a suit before they finally abandoned the tollway. I was living in the area at the time.
However, the DFW tollway is the exception, not the rule. For the rule, look at the Dallas North tollway which has been around since Jesus was in elementary school and has little likelihood of EVER going bye-bye.