why is it against the law to take a picture in Bulgaria
I don't think you are right to state that it is against the law to take pictures in Bulgaria. I have been there (several times) and took plenty of pictures and vidio. As in many other places around the globe taking pictures of private people might require a permission. And there are palces where one is not supposed to take pictures at all: e.g - military bases, museums, churches, holly places, certain caves, private shows,...... etc......
Other people asked questions on various topics, and are still waiting for answer. Would be great if you can take a sec and answer them