I'm guessing at this point, it's got to be a lot of people. Many people (like me) can't get reliable delivery of packages at their home. It's really common in cities.
So why is this still a problem with so many merchants, merchant gateways, and credit card companies like Discover? In this case, Discover is the culprit. A credit card company. A credit card company. Not the kind of business of renowned prudence and foresight.