The net revenue would be lower than $200M. There are substantial costs associated with ticket revenue collection, from the % payment gateways charge, the maintenance and replacement cost the devices and turnstiles hardware, all the software and people who have to manage and enforce the system.

The issue with SF (unlike Iowa city) is that free for all everybody is going to be harder sell to voters when there is large amount of out of city traffic -travelers and greater Bay Area residents who do not pay city taxes.

What is more realistic is extend subsidies to all residents of the city beyond the current programs for youth/seniors/homeless/low income etc.