However, having said that, the piece doesn't suggest that people forget to actually fill their prescriptions (ie they don't go and buy the drugs prescribed by their doctor). That would lose revenue for the pharmaceutical companies. It simply says that having bought the medication, they forget to take it or take the wrong amount. They have already bought the medication so the drug companies didn't lose revenue there either.
They would lose revenue if the noncompliance behaviour included not bothering to buy the prescribed medication. My personal feeling is that it probably does include that but it's not specifically stated in the excerpt you have posted.