The number of those killed by drunk drivers has dropped from about 25,000 a year in the 1970s to closer to 10,000 a year today. This is definitely a significant, so why is drunk driving still considered a social problem?

An informal structure in a bureaucracy would be something like so-called "office politics". where there's a formal structure set up for the organization, but then an informal subculture as well that has a way of organizing the bureaucracy further. this can be positive because it sets up an added degree of organization, albeit informal, within the bureaucracy.