To be more clear I visited an Amazon FC during the first week when I joined Amazon in one of their operations teams, in which I have then spent 4 years.
There are processes in place and physical things that are completely different from what the original commenter says and those things prevent the issues (having items on another shelf multiple feet below where they should be) from being possible.
Another ex Amazon guy here. I visited the Dunfermline FC, did picker training, and shadowed a picker for an hour. I also followed company email lists and FB groups for years. It became extremely obvious to me that what I saw in my curated experience was nothing like what I was hearing from the other FCs.
So, even though from my experience I can't see how items could be 'shuffled' out of their bin by mistake (other than falling on the floor and being chucked in an amnesty bin or onto a random shelf, but that seems like a rare case) I also wouldn't find it super surprising to find an FC which just uses a completely different way of organising stuff.
That said, I wasn't in ops. Perhaps you had a much better birds eye view of every single FC organisation scheme? More details would be greatly appreciated.
A close family member worked in an FC for 3 years. They agree that what the original commenter said happens ALL the time. Maybe you were only shown a shiny new FC, but the older ones are often much less organized. Depends a lot on local management too.
There are processes in place and physical things that are completely different from what the original commenter says and those things prevent the issues (having items on another shelf multiple feet below where they should be) from being possible.