We generally try to do things that give a return on investment and don't burn money for no reason. This one most certainly had the ROI. It took 4-ish people to build it in under a year and it removed significant pain and increased developer velocity for hundreds of other developers. Many of whom are working on things that allowed us to be profitable at our IPO.
We're not just a shopping cart product. I thought the same before I first joined but it turns out getting groceries to your door is incredibly hard to do at nation-wide scale.
Sounds roughly right. Though not all of us were full time on it at all times. We also paid that just once about two years ago. It has been part time feature and maintenance work since then.
Now run that same estimate assuming we saved 600 engineers only 1 hour per week (a very conservative number by our research and feedback). $120/hr * 1 hour saved per week * 4 weeks * 600 engineers. We paid it back in less than four months, conservatively.
We're not just a shopping cart product. I thought the same before I first joined but it turns out getting groceries to your door is incredibly hard to do at nation-wide scale.