That's an interesting argument, but I'd be surprised if you can find any court case stating that you can copy a map without violating copyright. In the USA, the Copyright Act of 1790 specifically included maps and charts (they were not included in the equivalent British statute of the time).
I'd further suggest that putting the map into computer-readable form does not change its copyright status, not even if you start calling it a 'database'.
Of course the underlying facts themselves are not under the control of anybody, but that does not mean you can copy the representation of them. Similarly, anybody can photograph the Statue of Liberty, but it is not allowed to take somebody else's photo and copy it without their permission. You can certainly use it to learn some facts, such as 'the statue has a spiky hat', but it's not safe to make a copy of the representation of those facts without some clean-room process.