Starbucks baristas can't keep up with mobile ordering volume

Starbucks has been very successful in migrating customers from placing their orders in stores to its mobile app. The problem, according to some of those responsible for completing those orders, is that there are way too many to keep up with in a timely fashion. One of the issues around this appears to be the ability for customers to request large numbers of modifications to their drinks, which adds complexity to preparing them.