Making fare evasion impossible on public transit has tremendous impacts on safety, maintenance spending, and vandalism. SF saw a 98.2% decrease in maintenance hour obligations instantly.
There is a large segment of the progressive population that believes in free transit. It's easy to see why this idea is so popular - transit is used by poor people, needs more funding, and we should encourage more people to take it.
So why are our cities forking over hundreds of millions to install barriers to block fare dodgers? Why not use the money to allow more people to ride for free?
The answer is our transit systems SHOULD be adding barriers to people getting on transit. NYC's MTA and SFBART won't say it, but the purpose of cracking down on fare evasion is that it blocks the unhoused, people with mental difficulties, and people who don't have a card to tap with from entering. These expensive gates don't pay for themselves because of an increase in usage. It's because the risk of vandalism and crime drops significantly. Vandalism in SFBART is near 0 now - this helps a lot with spending, aesthetics, and provide a safe environment to encourage middle-upper class professionals, and women, to take transit. And the more women and wealthy people take transit, the more reliable and safer the system becomes.
The fare doesn't matter - make it 0.5$. However, the person SHOULD be in a capacity to have the financial means to pay this and have the mental capacity to avoid fare dodging.
As for those who are now shut out of transit - if you are unable to pay the fare or don't have morality to avoid fare dodging, it should be treated as emergency social services/healthcare can deal with. Not public transit.
We could even make the fare 0.01. The person just has to be able to safeguard a card and pay with it.