As far as i know, both Instacart and Postmates make money with every delivery. They used the last two years to figure out what to charge and when. Both get kickbacks from select merchants, both are in a heavy growth phase and both have tweaked their algorithms to either allow for multiple deliveries per hour or use in-store shoppers for faster access to gods. What they are doing is working and it looks impressive to me. The really interesting differentiator is that one of them can become a giant supermarket without owning any warehouse space and the other has a shot at powering local deliveries everywhere. But then again, maybe they both still figure all this out.