Same happens here. Pedestrians will walk in the street with a sidewalk just feet away.
They do it for the same reason joggers do it. None of them want to pick their feet up but an inch or two off the ground. A street is much more level than a sidewalk that has rises and valleys in it. For people too lazy to watch the sidewalk and pick up their feet to keep from tripping, they just walk down the street on their "public" phone call oblivious to traffic. I think these type of pedestrians actually dare vehicle traffic to hit them.