That's actually got nothing to do with zoning (surprisingly); it's the road type. Buildings with AIs inheritng from PlayerAI (basically, that's any player-placeable building, including fire stations and schools) will complain about no road access if they're not placed near a road without pedestrian access.

This is because all such buildings need pedestrians to be able to reach them (and no, adding pedestrian paths manually doesn't work, unfortunately). You'll note that despite the complaint they still operate - firestations still send out fire trucks, for example.

And you've probably noticed that this doesn't apply to normal zoned buildings (PrivateAI).

EDIT: Spelling, originally had 'PrivateAI' instead of 'PlayerAI' in first paragraph.

引用自 algernon：

That's actually got nothing to do with zoning (surprisingly); it's the road type. Buildings with AIs inheritng from PrivateAI (basically, that's any player-placeable building, including fire stations and schools) will complain about no road access if they're not placed near a road without pedestrian access.

This is because all such buildings need pedestrians to be able to reach them (and no, adding pedestrian paths manuall doesn't work, unfortunately). You'll note that despeite the complaint they still operate - firestations still send out fire trucks, for example.

And you've probably noticed that this doesn't apply to normal zoned buildings (PrivateAI).

oooooooooooooooooooooooh this makes sense, thanks for the info!