What does R or D have to do with this? It seems to me the California law infringes on the constitutional right of free association, amongst others. Why can't I be an independent contractor pursuing a variety of disparate interests? Why do I "have" to be an employee for only certain types of work? And this CA law plainly doesn't outlaw "gig" work for all - it has way too many exceptions.
Either there is no independent contracting for anyone or it's available for everyone, regardless of industry. And even if CA tried to outlaw contracting for all, I suspect it'll get struck down as unconstitutional.