This is worsened by many people doing a poor job of providing said feedback, for a myriad of reasons: because they never learned how, because they were never in an environment conducive to doing so, because they flat-out just don't care, etc.
Not to mention, there's also the fact that some pills are just straight-up hard to swallow. I've had to choke down more than a few of those, and it took a long time for me to develop the maturity to do so productively.
An NDA doesn't fix any of these problems.