Again, thank you. I should indeed have goggled, just now I spent more than 5 seconds and am fascinated by the whole manufacturing process.
I should not have extrapolated wildly; many of the batteries I use are obvsly mere rebrands, and most of them look extremely similar inside and out once fancy labels are removed. Or similar. Or alike enough.
But this is prolly a result of evolution - something that works, and is easier or cheaper to manufacture, starts becoming what all cells look like. I'll google that. 
Also, my experience is very limited to batts that are of a certain size range and aimed squarely for a narrow use case, so it should not surprise me that they are all very alike.
Of course cells with the same chemistry are cranking away in a vast number of deployment scenarios and again, it shold be no surprise that many manufacturers are providing cells in all manner of physical forms made with differing (and proprietary, as you pointed out) details.
Now I go fly. 
a7