[rovek]

We drive on the left, which means we walk on the right (to see traffic coming), so I guess it stems from the latter

[YPPH]

In Australia, we drive on the left, but on escalators we pass on the right just as the parent comment envisioned.

[alisonkisk]

In the US, we walk at traffic when there are cars on the road but the passing lane is the same (left) for driving roads and for pedestrian multi-lane "roads" like escalators.