Not sure if you're trolling or intentionally turning a blind eye to one of Bitcoin's flaws.

Fungibility has nothing to do with "choosing to see or ignore information" or "choosing to treat some coins as new". Any information that CAN be known is the problem. In Bitcoin the entire coin history can be known. With cash, the entire history cannot be seen. No matter what you choose to believe, there literally is no record of who held the coins and when.