@Dominic730 100% its a numbers game. As Frank always refers to his sorter the game becomes volume. If you are a smaller sample size , you have to really change the tuning of the sorter.
I had a side run in a hobby penny business. pre 1982 pennies are made of 95% copper and there was a stint ( still is ) where the metal value exceeds the currency face value. If you process enough, you get these and can bulk them up and sell them ( i think the market for this is non existent at this point) . Similar concept if you know 1964 and before , change was silver. So if you process enough change you can find these quarters ( where you pay 25 cents) and they are 3-4 $ a piece.
When you get into the commercial operations , you can sort out a bag of quarters that cost you 1000 ( face value ) but its worth say 12 ,000 -13,000. If you sort enough pennies, you can even stumble upon the rare gold coin ( which might be worth say 100 plus dollars ) that costs you literally one cent. The commercial sorting operations obviously have their costs,( equipment, employees, insurance ) but the principal is the same. Its all about volume, tuning etc .
As @Greg probably knows, there was a stint there where a canadian nickel 5 cents was worth say 20-25 cents and the government was smart enough to realize this ( and outside vendors) that started processing all the coins and pulling this from circulation ( Greshams Law) .
There are legal components to this ( exporting currency , melt bans etc)
While i def sidetracked on this but just driving the point home about the sorter, probabilities , etc. I spent way to much time on this venture but i learned a ton and figured id share some monday reading ( in case anyone else doesnt want to get back to work - like me right now)