1 Lucas: Well, we’re through the wire fence. Now what? How do we get into the building?
2 Dustin: We do what any adventuring party would do. Search for secret doors!
3 Lucas: Don’t be stupid. That’s never going to—
4 Dustin: Found one!
4 Mike: And he’s not even an elf.

Searching for secret doors is a time-honoured staple activity in Dungeons & Dragons games. For some reason, every architect and builder loves to make roughly 5-10% of the all the doors in any given structure secret - so well hidden that you can't find them without deliberately looking for them. Often the really juicy stuff, such as rooms laden with treasure, is hidden behind secret doors. So of course every adventuring team worth their salt has to inspect every square metre of wall as they explore, just in case there's a door there that they can't see.

Elves have some sort of innate ability to be better at detecting secret doors than anyone else. It's never explained how a race that values living in the wilderness, among forests, has developed the ability to spot secret doors better than races that live in actual buildings and cities.

That's a bit like if humans developed the ability to smell rabbits inside burrows better than dogs.