It's not about hiding the facilities from locals, it's about hiding them from satellites. Or at least providing enough uncertainty that the enemy doesn't know for certain how many or which installations are where.
More morbidly, in a first strike scenario you want the enemy to waste nukes on actual farmhouses it couldn't tell for certain were launch facilities or not. Then even if no facilities are missed (something you would be hoping for), that's still fewer nukes to be dropped on cities and conventional military installations.
There is no point dropping a nuke on a single tactical target. Nukes have a blast range of miles and a regular missle can take our a facility just fine.
That's a decommissioned silo. When it was operational, it would have had the fence and usual such around it. The Northern Tier facilities are mostly underground, too. The actual silos (Launch Facilities) look like basically nothing from the top, were it not for the fence and nasty signage starting "Use of deadly force authorized". Also the Southern Tier silos had the launch control facilities integrated with them.
"Excuse me, we're looking for Sierra 7." "Yeah, it's down this road for a mile, then left on 127."
And the Soviets wouldn't have been fooled either. So they look like military installations.