That's partially BS generics are not always the same as brand name drugs. The manufacturing facilities are not the same the suppliers of active ingredients and the degree to which they are purified are not the same. So if insurance is covering brand name drug it's actually better it be prescribed vs generic.
The FDA standards for generics are 80% to 125% of AUC and Cmax (measures of bioavailability). So you could be getting up to 20% less or 25% more drug with a generic than the brand. Sometimes that matters, sometimes it doesn't.
A great example of a generic drug problem is with Wellbutrin, used for smoking cessation and as an anti-depressant. The FDA allowed Teva to market their 300 mg pill without actual bio-equivalence testing (they just extrapolated from the lower dose) and as a result a lot of patients had bad side-effects. Teva recalled the product.[1]
This company was fraudulently claiming that the drug profile of their generics was identical. Thanks to a whistle-blower the company was fined $500m by the FDA, after years of legal wranglings.
