“They also reveal cracks in Starbucks’ business model, which has changed in response to customer demand from a predominately sit-down coffee shop to a mostly drive-thru and mobile takeout chain.”<p>This is the real reason Starbucks sales are tanking, which has been pointed out by many people. The app, with a million customization options keeps the baristas busy and when you try to order in the store you get crazy wait times.