Because the name "Big Brother" was already taken

from here and here

Candid Camera and all the hidden camera shoes that came after it were always a little creepy when you think about them secretly recording people without their prior consent. That's pretty much the same thing that the new surveillance comedy show from Amazon will be as well, except this time the cameras will be everywhere, and it will give people yet another reason to participate in a surveillance state that feeds data directly to police without permission.