I think the thinking was that falsifying banknotes would be too easy if there were many different ones. Yes, people could turn over bank notes to check the comm

I think the thinking was that falsifying banknotes would be too easy if there were many different ones. Yes, people could turn over bank notes to check the common side, but that’s annoying. For coins, that’s less of a problem because they’re worth less and because it’s harder to make lots of money with fake coins (you’d have to make lots of them and, more importantly, find a way to spend them rapidly. Paying an expensive car/watch/smartphone/etc with coins is highly suspicious)