Not surprising. These apps work on an on-demand basis. It's just not feasible to pay somebody an hourly wage when you can't guarantee any work to be available for them to do at any given time. And you could then make the argument of "if they can't afford to pay them like employees, they shouldn't be in business", and I'd like to agree, but ultimately there is a huge demand for this line of business to exist and that isn't going away any time soon, especially as car ownership is decreasing in some areas these days. Most of these apps have yet to ever turn a profitable quarter, as is it, so increasing their cost of business isn't exactly going to result in everybody getting raises.
Also, there's generally a pretty big reason why people take these jobs over a traditional 9-5 in the first place; a large amount of these workers prefer working their own hours and not having to report to a superior. Or due to whatever life circumstances they might be experiencing (mental health issues, homelessness, disability, criminal history, etc) may prevent them from securing a "normal" job. A majority of the people working on these apps would find themselves unable to keep their jobs because they couldn't be available on time for whatever reason they may have. Ultimately, classifying them as employees would hurt a lot of them, and will likely drive them to another gig business (like food delivery or handyman/TaskRabbit, etc) where they'll be exploited the exact same way all over again, but now without any of the stability they had with their previous work.
I'm not saying all this in defense of these apps. But I do work on the corporate side of this industry and talk to the contractors on a daily basis, so I'm pretty familiar with the motives people typically have for signing up to work for these apps. As odd as it may sound, many of these people want to be contractors; they just want a better cut of the payment.
It would be great if there was an alternative that could cut (or at least reduce the need for) the middleman and allow users to be paired with a contractor directly. I'm surprised that there hasn't been any real attempt to make one yet.