Odd... I've been down Floridian Way many times and have never seen any signs....
I've seen the signs at the entrance to the backstage areas yes, but this is not a backstage area. It is a "normal use" road. Face it, you came into yet another thread, spouted off without thinking, and then got slammed for it. There are thousands of other threads available for you to go start something else in. I hear there is a ripe "Hyperion Wharf" thread of a February 22nd vintage that would go well with your meal. And it only has 48 posts too! Go get em!
All joking aside, you are right in one regard. Disney does not like "backstage" photos to be taken. That much is true. I would be lying if I said that most of us would not love to see some of the things that go on backstage. But it isn't typically allowed. But the photo you so promptly started chewing on was from a normal, everyday, guest road. If Disney doesn't want us seeing the top of a tent (yes, it sounds just that ridiculous) then they would build a 100 foot wall.
Ohhh, and another thing, if this photo got your dander up then you might want to steer clear of several Disney shows like Modern Marvels: Walt Disney World and Samantha Brown's Disney Holidays. They both show the little man behind the curtain.