What's Postmates moat? Having never used it, I don't necessarily see the 2.6b$ value in a smaller delivery app that is only really used in some areas of the US. Though I'm sure there is something I'm missing and 2.6b$ is probably less expensive than the cost of pricing Postmates out of the market especially considering it's an all stocks deal. It's just that delivery seems to be easily scalable and easy to just dump…
Network effects are the moat here, much like for ride hailing apps. More drivers signed up on the app means that the service times for customers are improved, and more customers using the app means less waiting time and dead mileage for drivers.
There's an illusion of network effects due to the investors willingness to burn their own money. Otherwise, like the actual transportation industry it's just a low margin business with tons of competition.
Meaningful network effects don't just make your company marginally better as you get bigger, that's true for virtually any business. It has to be shown that the size actually makes you run away with it instead of just leveling off.
The same is true in the fintech industry with all these much hyped neo-banks running on debt. Internationally they all tend to lose to local competitors because knowing your market and getting the details right is more important than scale.