From the NYT: https://www.nytimes.com/2024/08/26/nyregion/nyc-bus-subway-fare-evasion.html

Fare beaters might also feel emboldened, experts say, because heavy traffic and a lack of bus lanes means that bus service can be slow and unreliable. For some riders, it is simply not worth the price of admission. The pandemic also reinforced the perception that fares were optional, after the authority made bus rides free for a few months in 2020.

Once you give something out for free, there’s no turning back.