> Conversely, what would happen if someone took pictures of cars going in / out of NSA/CIA/FBI facilities on a regular basis and posted them online?

I would imagine that person's life would be made very difficult. Even outside of these lettered agencies, I would imagine if someone created a system to capture the license plates of the cars used privately and publicly by government members or high ranking executives in organisations tied to the government they would create a very bad situation for themselves.

If anything has been made more than blatantly apparent in recent years it is that there are one set of rules for us and another for them.