You’re moving the goal posts considerably here. It’s not about comparing the cost of the ticketing system to the total cost of operating the entire system.
The price of fares (zero, high, or otherwise) has no effect on the price of oil, tires, and other capital and maintenance costs. (Ditching fares would lower wage costs, of course.)
It’s whether the net social benefit of fare systems is less than the net social benefit from not spending money on fare systems.
Tolls depress usage. The net benefit of a toll road is less than a public road. You’re right that they can cost society more overall than roads funded in other ways. (And “operators of toll booths” wasn’t meant to mean a single lonely minimum wage attendant, it’s the owners and private corporations that win these kind of contracts)
In 2017 the total income (before expenses) of the line item “Supply of transport services” was 227 million dollars. That is less than the 160 million you’re estimating is paid on just the Myki system (less other fare-based capital outlays, wages, and maintenance) and enforcement.
It’s still arguably not as good a deal as foregoing the 60 million as a society and seeing that same money get circulated in the local consumer economy, even beyond any other benefits from having a frictionless public transport system.