The north/south thing could just be climate. In the north, there's at least a portion of the year when a dog has to be kept inside. This may also create a preference for certain breeds, as well as for dogs that have a better temperament around humans. But I would echo the sentiment. In the decades that I've been a cyclist in the north, I've been chased by dogs only a handful of times, and was able to confirm in most of those cases that the dog was probably harmless.