I believe it's therapeutic equivalence that the FDA is lax on, not bioequivalence. Bioequivalence is just "does it deliver the same amount of the active ingredient," theraputic equivalence is "does it deliver the active ingredient in the same manner." The active ingredient is the same, the inactive ones are where the difference lies. Usually, they're similar enough that it doesn't really matter, but some drugs really do benefit from buying the name brand.
A good example is with methylphenidate generics - you get the same amount of methylphenidate, but the name-brand extended release is far more effective than the generic extended release because it spreads the same amount of active ingredient over a longer period (the delivery mechanism created by the inactive ingredients in some generics is subpar).
Occasionally, you'll get non-bioequivalent generics that slip through FDA approval, which happened to some methylphenidate generics [0][1]. I remember getting switched to the name brand when this came out, as the supplier for all the pharmacies near me used a non-bioequivalent manufacturer. (Authorized generics don't have this problem since it's literally the name brand with generic labels slapped onto it, but the one the nearby pharmacies could get through their suppliers was not the authorized generic.)
[0]: https://www.fda.gov/drugs/drug-safety-and-availability/quest...
[1]: https://www.reddit.com/r/ADHD/comments/3af86d/fda_rules_2_fo...