Because seamless/instacart/hipmunk/service X aren't individually incentivized to use a generic interface. It's the same reason you have a gazillion logins, each

Because seamless/instacart/hipmunk/service X aren't individually incentivized to use a generic interface. It's the same reason you have a gazillion logins, each one wants to be the One True Source. (After years of struggle, FB/Google/Twitter managed to hammer that down to "just" 3 choices.) In addition to the 20 apps a user needs, there's new ones they don't know about ("Where do I get flowers again? Car parts?"). The value proposition: People can fire-and-forget an order for anything. Someone else handles the details. People with more money than time -- a great market to serve -- prefer to trade the former for the latter. Cheapo McCouponClipper will sift through the apps individually. Do you go to the grocery store and tut-tut people in line? Don't they know they can get batteries cheaper at BatteryWorld? Vegetables cheaper at the farmer's market? Windex cheaper at Bob's Industrial Cleaning supplies? Why are they at a general-purpose store with a larger markup? But it doesn't matter. The incredulity of objectors who ask "Why don't you just install 20 apps and save some money?" will be superceded by people who just want to use the service.