High-income consumers buoyed quarterly results at Uber, DoorDash, and Instacart. Bloomberg/Getty Images Uber, DoorDash, and Instacart targeted high-income consumers — and boosted their quarterly earnings. Their latest offerings, from hotel booking to coffees in an Uber Black, take aim at affluent users. The companies are still maintaining offerings for customers looking to save money. Black-car rides, paid memberships, and other offerings for affluent consumers are paying off for Uber, Instaca