There's no real reason for it not to, other than superiority. I ought to mention though that yesterday I was riding along the Bristol-Bath Railway Path about 5:30, rush hour. At one point the path crosses the busy A420 (this used to be a level crossing back in ye railway days and the signal box which controlled the gates is still there) by a Toucan crossing, and despite it being rush hour with all that normally implies for waiting times, the lights changed instantly on pressing the button. It seems in this case they've decided there is enough cycle and foot traffic to justify response; though not to justify the lights being defaulting to green in that direction and having to be triggered for the other.