To be fair, I see the same thing from the other side of the counter. I work in industrial/ag supply. Bearings, hydraulics, etc. I've got a million stories of customers and some of the **** that comes out of their mouth would make you shake your head.
Basic story? Guy comes in, looking for a bearing. Knows the shaft size, outside, etc. So I ask him:
"Set screw or eccentric lock collar type"
Blank stare
"Does it got two set screws at a 45 or 90* angle? Or does it have a little collar that comes off?"
"OH the collar kind"
Go to the shelf. Get it. Set it on the counter. I'm punching it up, he's opening the box and looking at it. The eccentric lock collar bearing is just that. A collar that has an "eccentric" or "cam" style lock. Spin it around the shaft, the two cams mate, hit it with a drift - Done. He starts spinning the collar around.
"This ones broken, it won't lock"
My turn for a blank stare - "Yeah, it won't lock without a shaft in there...."
"OH duh"
And on my story scale, that's about a 2/10. Ask me about the hutterite who can "spin" his hand at "exactly" 411 RPM.