That's definitely part of the problem – especially when it comes to the
amount of a particular drug being prescribed. A lot of the addiction/dependence exposure involves diversion, i.e. the people using the prescription opioids are not necessarily the people who they were prescribed to. Often someone will start by buying leftover/extra pills from a friend/acquaintance, become physically dependent, find someone else when their friend runs dry, start running low on cash, and then finally break down and go for the cheaper option (heroin).
I don't think I've ever been prescribed less than 30 of an opioid pain reliever for an injury. Sometimes with refills. Five or ten, with the ability to call the doctor for a same-day script if I were still in pain after those, would be infinitely preferable.