“And the Greeks themselves don’t know that because...?
For the same reason any language group fails to follow God’s instructions - the lure of pagan and religious ritual.
Why did the Israelites make a golden calf and worship it - despite having God’s 10 Commandments in their own language?
Maybe that's not what God's instructions really say. It's much more likely that you are understanding the Greek wrong than it is that millions of Greek-speaking people, for whom it is their native language, have understood it wrong for 2000 years. Occam's razor.
BTW, there is no "lure," "pagan" or otherwise, to going to confession. It's painful and humiliating. It's supposed to be. It's just not as painful and humiliating as the punishment Christ suffered for those same sins.