I think this is an unnecessarily cynical take. Money certainly matters in politics, but it can't buy enough votes to win on its own. The contingent of people who genuinely dislike AB5 was very motivated, and clearly sizeable
Prop 22 is viable this year because of the COVID-19 pandemic and the dire straits so many are in. It's supported by those who need any source of income they can lay claim to, no matter its quality, and by those who know someone like that, and so on. In a year (or a society) in which fewer people were so desperate, I would very much like to believe that this perverted lawbuying would be shot down by a wide margin.
Money can't buy love either, but being a billionaire makes that way, way, way easier.
So it can't buy something with 100% guarantee, but if it gets you to 90%, the difference is ... academic.