It's obviously to keep the liability off of Uber's balance sheet.

>What's it called when the gigsters have to front their own capital to get the gigs? Pay to play?

Normal freelancing/independent contracting. And yes, there's a dispute about whether the classification is legal, my point is just that there it's not something Uber invented (edit: or any of the other on-demand startups).

No. Its like being paid per each function of code developed. There is a segmentation of work into deliverable units(rides, deliveries). If programmers were replaced by gig economy, it would look like freelancers getting paid pennies for creating tiny pieces of code(with large competition between them for speed and performance): e.g. a gig where you write function X of project Y, which is then graded for performance and compliance and paid 60 cents, with a twist:you are only paid if your function is the best one among all submitted. With gamification and ratings, the competition become very fierce and people get near zero income, making the job unsustainable except for those living in third-world countries.

So that the loss aversion element of that investment makes them work like slaves