It was commissioned by Uber but conducted by an independent research firm, and the methodology is documented, so it's up to you how reliable of a source you find that.

Since these are major lawsuits and it's also becoming a pretty big story in California, I imagine if there are significant flaws here or if there are other reputable surveys that have found the opposite, that those will start to surface. So far I haven't seen anything to that effect.

[0] https://www.cadriversurvey.com/

Edit: I missed in the irony in your comment as well on first read. There's an entire side industry devoted to helping workers maximize their profit, and many seem to have success doing so. That seems like a good thing, at least for those who want it? Compare that to other industries like Amazon warehouse workers, where many are full-time employees. It doesn't seem to have helped their working conditions much as there are a lot of complaints about the job, and if certain employees are more productive the company pockets the savings rather than the employees being able to make more money.