It's a thing. But never a correct thing. AFAIK. Thankfully less common today than in my younger days. At least it is here.

I think it comes from the general consensus, that a pedestrian walking on a road with motor vehicles, should be walking into the traffic. Parents walking will frequently be accompanied by their children on bikes as they walk around the neighborhood. And of course those children are on the same side as their parents. And they just get use to being on the wrong side and think that is correct as they get older and go off on their bikes without their parents.