Imagine your city is a grid...N/S streets are numbered, E/W streets are lettered.
Toll roads wouldn't be efficient if 5th-18th ave are toll roads (operated by multiple companies/agencies) and then Fst-Hst and Ost-Xst were also toll roads. You'd never be able to get across the city.
Except if you have interoperability laws in effect (like in Switzerland you can take a bus, a boat, or a train with the same ticket, yet they are different companies).
Toll roads wouldn't be efficient if 5th-18th ave are toll roads (operated by multiple companies/agencies) and then Fst-Hst and Ost-Xst were also toll roads. You'd never be able to get across the city.