They're kind of a real thing. Look up Generic Brands. I remember seeing them in the early 90s. The one I remember most was "Beer". White can with just "BEER" written on it.

I think they've started to eventually jazz up their packaging so they just look like rip-offs now.

That's a bit underspecified, but I can think of some contemporary items on the shelves whose richful branding communicates about just as much actual information.