Another thing, is these platforms have more than one kind of participant, ones who utilize them as their main source of income, and those who utilize them as complementary source of income or as a part time/college/uni job.
If these platforms would simply be a platform (who like yelp) let the provider sink or swim based on ratings, then they could avoid the problems stemming from their requirements [which makes the platform less ad hoc and more rule based thus leaning toward employee - yet the fear would be a degradation in service to end users and thus a threat to platform viability]
One thing I'd like to know is whether people doing lyft or über full time do on average better or worse than their yellowcab counterpart.