Error coins - what are the odds?

My latest bank circulated roll find - (presumably) a fully split Jefferson nickel planchet. I got the reverse with a D mintmark, and the coin weighs 4.3 grams.

The obverse is totally naked. Pretty amazing for only missing 0.7 grams. It's clearly circulated. We're all collectors - can any of us imagine holding that coin and not noticing something awry? And yet every other person who touched that coin for at least the past 46 years spent their $.05 instead of saving.

Out of all my bank wraps I've searched in the past year, this takes the cake. I've had a questionable D/S clad Roosevelt and a Wheat Cent with 3 really minor clips. Varieties are around, sure, but errors have been truly rare.

Quality control at the mint, even in poor years, is pretty amazing.