On a project I worked on, the government had this idea that we should put an inference engine (essentially an AI) into our software (which ran on a military radio). The idea was that it would be able to process XML-coded regulatory instructions and be able to develop a spectrum-use strategy that followed the appropriate regulations. It added unfathomable complexity, along with a Prolog interpreter, to what was otherwise a tractable system.

My guess is that the "500 million lines," to the extent it isn't pure fiction, is not actual program logic. Rather, it's data files capturing the legal and regulatory distinctions between the 50 states, all the different providers, etc.