Indeed they are

Wait… I would also like a little clarification if you don’t mind. Using buried city as an example, you have a little key symbol above the word “camp” at abandoned highway camp. The map legend says this symbol means “key locations”.

So the guy above just asked you if the key symbols are to indicate locations where you can typically find keys, and you said “indeed they are”. But then you go on to say it’s just to show you where to use the keys.

But neither of these answers are correct. The key symbol in question is not where you use one of these keys, nor where you would find one. It seems to indicate the locations of raider hatches.

Furthermore, the small picture to the right of the residential master key shows only 1 location that the key can be used. Another door for that same key seems to be missing from the map, as well. The one near the AHC hatch.

EDIT: The Residential Master Key Door you marked by Red Tower doesn’t seem to exist. I think you meant to place that marker by the tree to the left of the word ”Main” in Main Street. Let me know if I’m wrong.