On eBay for certain scammy sellers, but not as a general rule.

And on Amazon, certainly not for items sold by Amazon or part of Prime. Again, only scammy third-party sellers.

I guess by definition if they’re doing such things they’re scammy… and aren’t 3rd party sellers the biggest contingent of sellers on Amazon? I mean, I found such listings for almost all of the things I recently shopped for, including water bottles, cooking appliances, sports shorts, coffee cups, camping chairs, usb drives, video cables, beach sandals, winter wear, multivitamin supplements…

Not quite a scientific study, but I always sort by cheapest just to check and see this pattern every time.

The distinction you make is technically correct, but a does not lessen the scale at which it is happening.