This is for products like TaskRabbit, Lyft, Postmates, HomeJoy, OrderAhead, and so on -- products that happen to involve some amount of each charge going to a t

This is for products like TaskRabbit, Lyft, Postmates, HomeJoy, OrderAhead, and so on -- products that happen to involve some amount of each charge going to a third party. They generally aggregate the demand and build the UI themselves, though -- without them, there is no product. [Edit: yep, what Zac said in the sibling comment.]