The reflective tape only reflects light from a certain angle, basically the light you shine at it is only shined back in the same plane it came from. So street lights don't reflect their lights to car drivers behind or in front of him.
^^^^^^^ this is the right and scientific answer^^^^^^^^^
When I began commuting by bicycle I ordered an expensive hi-vis water proof with reflective strips as the nights began to draw in. To test it I pranced around my poorly lit street while my wife sat in our car watching. As suspected, she couldn't really see me very well until the reflective strips were directly within the lights beam pattern (which, considering properly adjusted headlights should shine no higher than hip level, isn't very good) and hi-viz is only hi-viz in broad daylight, something to do with using the UV element of daylight to enhance the brightness I think. At night under typical artificial light those bright yellow hi-vis garments are no more use than any other light coloured clothing.
I quickly returned my expensive cycle jacket and decided to stick with bright flashing lights to get noticed. Hi-vis is good during the day and reflectives are only good when they are in a direct light beam coming from the same direction as the viewers point of view.
Tell your mate he is an A1, 1st class, fully paid up, prize winning muppet!