I lived in Chicago for several years and when coming back to eastern Iowa to visit family during that time would take the I-88 toll. I don't know what they did with those dollars but I don't think much maintenance of the roads was involved. I-88 was always in pretty bad shape.
I did the same for almost 15 years and man it is an empty stretch of road as well. Most boring part of that drive. No cars is nice but there's barely even a gas station.