There are several trains of thought on the painted/unpainted tag issue. Best anyone can tell (from research on the A-12 cars anyway) cars with vinyl tops didn't have painted tags, while cars without vinyl tops had painted tags.
Why, you ask? Simple. There is a theory (and some evidence to back this up) the fender tags were hung from a piece of wire in the area of the inside rear view mirror. And since cars with vinyl tops didn't get their roofs painted, there was nothing but a bit of overspray on the tags.
Remember, this is relating to cars built in the Lynch Road plant. I've seen other cars that had NO paint under the fender tags, which means they were on the inner fender when the car was painted. These were B body cars.
And once again, since I'm playing catch up on A bodies, I really can't say about the tags. But IF some early ones had ALUMINUM tags (which you never see on a B or E body car) then they may well have been painted, but the paint didn't stick like it would on steel.