Funny tag on fender- what is it?

Lots of cars had them, but the long ones especially got in the way over the years, so likely removed.

I can recall slicing my hand open on one when I was 19 when a ratchet slipped while changing a spark plug.

Yep, I ripped it off.

Some are also aluminum, so more susceptible to corrosion near the battery & in salt states.

I have seen the outlines on the backs on hundreds of fender tags over the years where the inspection tags used to be.

Some fender tags themselves also have inspection stamps in them, so not all cars at all plants during all model years used the same processes.