Privacy coins dont exist. They are just a cryptocurrencies. Money have to be fungible. And for a cryptocurrency to be fungible it needs opaque ledger. It is silly to call coins private, if they are just what money should be.
Privacy coins do exists just look out news on how countries like Japan and Korea are planning to remove complete the listings of this "anonimity/privacy coins" that is currently available on their exchanges. Some popular anonimity coins like Monero, Zcash, and Dash are more anonymous compared to Bitcoin thus making a shift from criminals doing illicit activities from the coins I have mentioned, even the authorities have said that they know that these cryptocurrencies now are being used to criminal activities.
They dont exist. They are just simply crypto currency coins. They are made as digital cash should be. They are made how Aristotel in 300 BC wrote money should be fungible :
http://www.marketoracle.co.uk/Article10370.html3.) It must be divisible. Money should be relatively easy to separate and re-combine without affecting its fundamental characteristics. An extension of this idea is that the item should be 'fungible'. Dictionary.com describes fungible as:
"(esp. of goods) being of such nature or kind as to be freely exchangeable or replaceable, in whole or in part, for another of like nature or kind."All coins that are not fungible like Bitcoin are simply not a cryptocurrencies, but a transparent ledger cryptocurrencies.