To sum it up, it's a complete mess and every country has different rules and also enforces them differently. After all these years I still have no clue what is

To sum it up, it's a complete mess and every country has different rules and also enforces them differently. After all these years I still have no clue what is actually an official ruling of anything because I've had no problem showing my driver's licence when officially I'd needed my id card (in Germany). Then there's the decade old widespread rumour that you need to _carry_ any form of id, which is completely wrong (with a few exceptions).