Two possibilities
There are generally two reasons for an American plug to have an absent ground pin. First it just came off and is stuck in a socket somewhere. Cheap stuff will do that. Second, someone removed it to fit the plug into one of the many sockets in the country that take only a hot and neutral pin. The second one suggests shenanigans of the worst kind given the location.
Incidentally, I've long expected ultra-secure establishments to go to "nothing in, nothing out" procedures where people are expected to leave everything, including outer clothes, in an outer locker room, proceed to an inner room in their skivvies, and then dress for the job. So many places just let the cleaners in and out with whatever they can carry or even put on a cart.
And to parody Douglas Adams, in some NSA location one might expect that "the difference between the amount you eat and the amount you excrete will be surgically removed from your body mass when you leave".