I can't imagine how this is enforced. Clipper cards and cash will get you on any bus without any sort of check to see if you're allowed. There is probably a lot of overlap of people who get banned the people who skip gates and fares.
If Walmart and Target can manage facial recognition for shoplifting, I'd imagine it's at least possible to do with a bus system.
Walmart and Target probably are a lot less concerned with accuracy than a fare collecting entity would be; any benefit from facial recognition is a plus for them even if it often either is wrong or fails to hit when it should, whereas with toll collection it has to be near 100% to replace other payment mechanism, and nearly never get a false hit (though misses might be okay) to be a convenience method when people are still expected to have a reliable method for on hand for backup.
Ah yes, the legendary facial recognition system—right next to the locked-up underwear and $1 deodorant. Flawless crime-fighting tech, really. /s