For those interested in understanding the underlying case law that AB5 codifies (a decision called Dynamex Operations West, Inc. v. Superior Court), my company, Judicata, published a visual (and tech-enabled) explanation of the decision when it was first published: https://blog.judicata.com/understanding-dynamex-the-californ...
Whether or not Uber drivers are employees or contractors under Dynamex and the ABC test is an open question, but the Uber explanation of the bill's impact is more or less correct.