"errors" occur at the US MINT up to the minting process. Not anytime after the coin is minted. Even coins get damaged at the US MINT ... as soon as it's ejected from the machinery and slides down a metal slide into a bin then a bag which then get other coins slam on to them and create scratches, etc. are damage .. called "bag marks".
yes, putting coins in your pocket, in a purse, in a coffee can are all situational environments that can create damage on coins.