If I may give a weaker, counter example with anecdotal data from Seattle: I have only used Uber three times, and the last time I asked the driver about unionization and he was very for it (so an n of 1). He explained that all of the risk is on the driver and that sometimes Uber makes it very hard to work. He gave an example of a friend who was driving and ran over a rock while pulling into an apartment complex. The protocol was that another driver came and completed the ride for the user. However, his vehicle was now flagged as 'in an accident' when the problem was a flat tire, which his friend was able to fix that day.

Unfortunately, by being flagged as an accident the friend couldn't work again for a number of days as there was some sort of vetting process to ensure the vehicle was working right (very reasonable imo). However, as explained to me, there was some hang up with Uber where he couldn't get vetted for much longer than usual and couldn't work. He thinks that being unionized would allow for more driver friendly policies that would have prevented this.