From a "fairness" standpoint, the ISTHA could/should go All Electronic, and do, essentially, Ticket-based/Mileage-based tolling, based on Entrance and Exit on the System.
Get rid of Mainline gantries, except on Endpoints, and have gantries at all entrance/exit points
Growing up in Northern Will/Southern DuPage counties, it was always weird to me that the toll you pay on I-355 has little to do with distance traveled, but simply what exit and entrance combination. Going from 75th St to 63rd St? 75 cents. Going from 75th St to Rt 59 on I-88? Still 75 cents. Going from 75th St to Butterfield/Rt 56? $1.20
I-Pass/EZ Pass makes it doable to do a true Distance-based system, more similar to the old fashioned "Ticket" systems you have going East in IN, OH, PA, NJ, NY, etc. And ISTHA already does Tolling by Plate, and has their website set up to allow Users without I-Pass/EZ Pass to pay online before getting a violation notice, too. Wouldn't be that much more a jump to go All Electronic