You are establishing weird timelines on these decisions. Uber, Lyft, etc set themselves up in California because they consider themselves tech companies. The state of California likely couldn't have cared less about the special class of workers they employed until the group reached a critical mass which obviously didn't happen before these companies were founded. I don't know specifically when they reached critical mass, but it was likely within the last 5 years. At that point it became clear that the state needed to do something. AB5 was one of those attempts.

Companies like Albertsons who could benefit from these businesses weren't willing to commit to embracing them until there was stability in the industry. For all the faults of Prop 22, it provides stability through its incredibly high requirements for repeal or amendments. Companies like Albertsons now have the stability they desired and will embrace these rideshare companies to save a few bucks by shifting a greater financial burden onto individual drivers.