They also have HVAC to keep the air wet. In those sorts of facilities, over-dry air is often a bigger concern because of static electricity buildup than is moist air.

I don't know of anywhere that does this. As far as I know, air conditioners will dry out the air they are circulatiing. My server room is deliberately kept cool and as dry as possible. Static electricity is not a problem because everything is properly grounded and the floor is not carpeted.

I couldn't imagine deliberately humidifying my server room, that would just be insane.