Put me in the naive category... I made sure anything I'd wasted was completely witnessed and signed/initialed and did the same if/when I did the witnessing but only cuz I was a stickler for rules.
I did have an incident with a pharmacy on a personal Rx I was taking. I had been on this med (with butalbital in it) for headaches for several years and using a national pharmacy chain, I refilled it while out of my home state. I got the bottle back to where I was staying but found the bottle was smaller than I was used to, so I counted them. The bottle was totally full with a count of 80. I called the store and complained that there were 20 less than the label stated. The answer I got? "We count everything three times!" I told them about the size bottle, the label, and my counting the contents, but just got the same "counting them three times" answer over and over.
I immediately drove back, showed them the full bottle, told them to count them (three times?), read the amount that was supposed to be in the bottle according to the dang label, and asked her to see if she could fit 20 more pills in that bottle. She took the bottle with abject attitude, stomped off to the back, and returned a sealed bottle from the manufacturer without apology or deference. I asked her when was the last time this place of "business" had last been audited. Her eyes widened then ran to the back to answer the phone.
Once I became a nurse, I would count everything I signed for from the pharmacy. I figured if it happened just once to me, it can happen again in any other circumstance any other time, any other place, and any other situation. Maybe I'm overly cautious, but, just sayin'...