Yes, everyone who deals with the general public knows how unstressful and dignifying that is. That is, besides having to deal with blatant sexism[1], extreme ignorance[2], elderly genitalia[3], stealing[4], destruction of property[5], physical violence[6], bigotry[7], etc.
Right, so you have 7 links to the same site, all written from the point of view of the wronged assistance. Wow. If that is not proof of nothing, then I do not know what is.
You should know that Amazon bought Kiva Systems earlier this year, so they'll be replacing human picking with efficient robot picking over the next couple of years.
Your job becomes to stand there on a foam mat and move whichever item the laser points at from the cart to the box. This job will almost certainly be automated in the next decade as well, with something like FlexPicker.
It's not intended as a proof. If you need proof that these behaviors exist, I'm afraid you'll have to spend some time in retail spaces.
Personally, I've seen all of these - and then some - simply by visiting shops in my daily life and knowing people who've worked in those places, and I'm reasonably sure that most people have as well.
[1]: http://notalwaysright.com/man-up-and-let-a-woman-fix-it/2136...
[2]: http://notalwaysright.com/spyware-is-strength/21253
[3]: http://notalwaysright.com/at-least-we-know-her-natural-color...
[4]: http://notalwaysright.com/to-conjugate-a-thief/20886
[5]: http://notalwaysright.com/customers-can-be-tiring/20828
[6]: http://notalwaysright.com/cuffed-red-handed/20707
[7]: http://notalwaysright.com/bigotry-gets-served/20336