I was wondering about the presence of runners in bike lanes a while back, and found out the law (in CA at least) is, they don't belong there if there's a sidewalk. It would be like running down a car lane. Runners are considered pedestrians, so if there's no sidewalk (chances are there's no bike lane), cyclists yield the right of way to the runners as they would any other pedestrians. If there is a sidewalk, a cyclists shouldn't have to swerve into a car lane to avoid a ped in the bike lane.

Part of what it may come down to is cycling advocacy groups have to work A LOT harder to get bike lanes put into general plans and striped on the roads, so cyclists may be justified in being a little possessive. Developers pretty much automatically put in sidewalks.