Under the current FAQ, these are the question and answers regarding tips:

Is tip required? Where does that money go?
Tip is not required. 100% goes to your Postmate for their effort on the delivery. If you would like to leave a tip, you are given the opportunity to add 10%, 15%, 20% or a custom dollar amount. The tip screen will pop up once your delivery is complete.

Can I tip my Postmate with cash?
No. Tips are only accepted through the app.

Postmates Corporate knows that the money paid out to couriers is hardly enough to make the time and effort of making these deliveries worthwhile. 100% of the cost of gas and parking falls upon the couriers and the couriers receive zero compensation for traveling to the pickup location. Tips are absolutely required in order for Postmates couriers to make a decent wage on this job, but Postmates Corporate, both with this verbiage in their FAQ and with the design of the app, wants to make it as easy as possible for the customers to leave no tip.

Postmates Corporate also makes it as difficult as they can make it for couriers to track how much they are earning by limiting earnings summaries, making key earning info only accessible through the fleet phone app, and making it easy for customers to not even address tips unless they use the app again. On top of that, they flat out say that cash tips are not allowed.

All of this is an effort by Postmates Corporate to encourage as much business from customers who don't want to leave tips on top of delivery fees, which amounts to exploiting the couriers for cheap wages.. By simply changing the verbiage on the FAQ to encourage customers to top and making them understand the couriers depend on tips to make the job worthwhile, tips would increase substantially. Furthermore, changes in the the app that would prompt customers to leave a tip in order to finalize the order would eliminate the practice of procrastinating leaving tips until it becomes difficult for the courier to even realize they've received a tip.

Postmates customers are paying for convenience. They can get almost anything from any restaurant or store they desire delivered to their door within an hour. People who do not want to pay for this convenience should not feel okay about stiffing the person who brings them their orders and should be encouraged to go out and get the items themselves, not exploit a courier. In order for this convenience to work best for both customers and the couriers, tips need to be considered as compulsory as they would be at a table service restaurant or any other delivery service. And Postmates Corporate can make this happen with simple changes.