1) Yes, personalization might have a bit of an experience tradeoff. We can try to mitigate this with messaging like "flash discount" or "just for you". But we also want to make it optional for merchants. In my experience there's still a lot of improvements from other things too like dynamically adjusting discounts and varying the discounts across products
2) One of the takeaways from my time at Uber was that certain predictors of discount efficiency held pretty constant across markets. A couple were conversion rate (if more ppl were going to convert without the discount, it's less efficient to give the discount) and profit margin. We're betting that we can train a model to generalize these trends across stores to create a bump in performance.
3) We'll be kicking off our first case study with a customer in a couple weeks. At Uber, just varying the discount across merchants on Uber Eats improved the profitability of the discount by 40% (mostly because we were able to take advantage of differences in commission rates across merchants).