It was very much on and off for many years. It was intended to cover the costs then go away. Instead they installed stream lined overhead tolls to not have to wait at the toll booth anymore and now it's just a perpetual tax.
It's also partially owned by outside investment (specifically the skyway from Indiana)
Very interesting. That still doesn't imply the "poor bear the brunt" (the original GP's assertion). Likely the inverse - since again, businesses and wealthy individuals are going to travel by vehicle vastly more than "poor" individuals.