Why only farms' foundations can be lamed?

I hate it when I drop a farm and my opponent lames them. Is there a reason why opponents can see your farms' foundations and not for any other building? Personally I think it's stupid and opponents should not be able to see the farm placement, just like they can't see pallisade segments, houses or any other building. Or have them all visible so any building can be lamed. I prefer consistency. Why do you think farms have this special treatment? And should 1. all buildings foundations be visible (so you could lame everything), 2. remove visibility of opponent's farm "foundations" (all buildings equal), 3. leave it as it is (please explain why should this remain as it is).