I think a good GM should be in conversation with the players about what their characters know: I as a GM know when my players are planning things socially or on operations, and I'm there having that conversation with them. That's what things like the Common Knowledge skill are for, and I never feel inhibited about just sometimes telling players things they'd know given their character backgrounds whether or not there's an NPC present (I'll probably use an NPC for it if they are there, but they don't need to be).
Obviously that takes more work for the GM and requirest that they know these things, but then again if the GM doesn't know those things, then they won't be in their sub-version of the setting and that's also fine.