If you price out low-income people, you do get relatively more revenue from high-income earners. But the low-income people also get less service.

The non-charge eligible trips of the low earners declined as well. The paper did not differentiate between sources of income, and I'm not sure how relevant that is.

So the "poor off the zones" stands. Of course it's a matter of opinion whether this is desirable or not.

The paper is available without paywall here: https://www.mit.edu/~hamsa/pubs/Craik-Balakrishnan-TRR2022.p...