There are many bike commuters where I live, but it is an urban area and everyone is going in a different direction. I will only pass someone if they are going REALLY slow, otherwise I will just slow down a bit as they are likely to go a different direction at the next intersection anyhow. We also have road traffic and lots of road hazards (potholes, cactus thorns, gravel, etc.), so I'd prefer to just slow down a bit rather than get in someone's way so they can't navigate the road properly.