As a child error coins fascinated me. I had off-center cents and 5 cent pieces and a tattered copy of Alan Herbert's 1974 book The Official Guide to Mint Errors. The book had an entire chapter on brockages. I had never seen a brockage.
Brick-and-mortar coin shops didn't have brockages, at least not in Michigan. Even at a really big coin show it was rare to see one.
When I started collecting ancient coins I was surprised to discover ancient brockages are not exceedingly rare. Sixty-eight ancient examples are offered for sale right now on an ancient coin sale web site, as compared to a single modern brockage. (The site has twice as many total ancient coins as modern coins, so a better comparison would be 68:2.)
Would ancient users of coins even notice anything unusual when spending a brockage? It seems hard not to notice a brockage, yet we don't see any evidence that ancient brockages were put aside. They appear alongside regular coins in hoards.
I was surprised to find a modern, circulated brockage recently at a coin show. Even more surprising, it wasn't in a fancy holder. It was in a junk box among similar coins from the region. This coin, a Nepalese one paisa from 1947, somehow managed to circulate in Nepal during the 20th century. It then made its way to the United States and a dealer's try without anyone noticing anything unusual. This suggests that brockages do not "jump out" to the average user or even to a casual coin dealer. Perhaps it really takes a trained eye to "see" brockages?
I would be curious to know of other modern circulated brockages. Does anyone collect them?