Superusers become the main course of food delivery businesses

Food delivery companies strive to convert customers who are attracted to discounts into the usual high-value users.

Part of their challenge is getting more revenue from customers like Jessica Knapik, a 31-year-old cosmetic tattoo artist in Detroit. She already has a subscription to the grocery delivery service of Shipt Inc. and places orders at Grubhub Inc. or Postmates Inc. if ordering depends greatly on …