I don't think there was one teacher that I had in college that didn't mention something about good graphic design being about solving problems. Making sense of a lot of information in the most efficient way possible is a bit of a textbook way of describing the position, admittedly, but when boiled down to a soundbite, that's what you get.
A friend on Facebook linked to this article, noting his frustration with parking in LA. But I was struck by a few things. The design is great of course, but I also admired the designers gumption to put up a sign herself and get feedback on it. Guerrilla design, without all that sloppy spray paint.