It also seems a bit disingenuous to say this is allowing an industry to write its own laws. It's just an ad-hominem - who cares who wrote the law? It's the content of the law that is important, and the process that it goes through to pass. In this case if it is voted on and approved by the public, that seems like a perfectly legitimate example of direct democracy.
(Whether you think direct democracy is a good idea for nuanced policy decisions, or whether what amounts to a constitutional amendment that can't be changed by the legislature is a good process for regulating a fast-changing new industry, are separate questions. Those are very valid concerns IMO. But that has nothing to do with the arguments you brought up).
Edit: and thinking about a precedent that this sets, I see that differently as well. AB5 was pretty clearly a bad law, and the legislators behind it completely shut off all negotiations with rideshare companies and were intent on playing hardball instead of coming up with a compromise. It was clearly all about retaliating against these companies that these legislators didn't like, with no thought given to how it would actually work or what would be best for constituents (as evidenced by just how many other industries, from journalists to musicians, were caught in the crossfire and had to be exempted one by one).
Given that, I think this sets a precedent to legislators that they actually need to do their jobs. They need to do the hard work of designing practical laws that will actually work for all of their constituents. Their job is not just to make bold symbolic gestures to fire up the most extreme members of their base, and if they do and they insist on doubling down on bad policies that work against a large number of their constituents best interests, it can backfire like it did with prop 22.