I couldn’t find any documents on percentage of riders by payment method, but [1] says that in 2025 they actually got $14M more in fares than they budgeted for, partially because of “increased ridership that is paying full — or close to full — fares.”

Looking at the list of options on [2], your observed 1-in-5 Clipper taps seems within the realm of plausibility; there are a lot of ways to pay for Muni that aren’t visible to fellow passengers. In particular, out-of-towners who plan to ride Muni a lot are likely to get a MuniMobile (or, for the old-fashioned, paper) pass; and a ticket to any Chase Center event also counts as a Muni day pass. You also mentioned monthly passes (I know a lot of people who get them from their company’s commuter benefits), and there’s also transfers: not only are “single ride” fares valid for 2 hours, but if you board after 8:30pm you can’t tap again, because Clipper can’t handle it and you’ll be double charged!

[1] https://www.sfmta.com/projects/paying-your-fares-keeps-us-mo... [2] https://www.sfmta.com/getting-around/muni/fares

>I wish they could do something about fare evasion.

Reminder that vast majority of the fare is covered by taxes (Roughly 87%). I wish they should just fund the remaining 13% instead.

It might not even cost that much more considering all of the expenses involved with hiring more staff (Salary/healthcare/pensions etc.) to collect the last 13 cents on the dollar.