This can also cause delivery failures the other way around - a friend in Germany once sent me a package but didn't bother writing the apartment number on it because she assumed the postman would use my name to find the right box. Instead it got sent right back to Germany. (Austrian bureaucracy is just as unforgiving as German, they just have different rules to follow...)
I wonder if some of the countries referenced in the thread have different laws regarding opening post - in England it’s illegal to open post that isn’t addressed to you, so if the postie did make a mistake it’s not the end of the world as the receiver would just pop it back in the letter box (in an ideal world)