The problem with reflective materials is that they all function, one way or another, by having some sort of lens or bead that reflects light. The thick, stiff vinyl stuff has it molded into the back side of the material, with a white backing. The gray stuff that you see stripes, appliques, piping, etc, made with, is a sort of coating that is heat-applied to some substrate material. In all of those cases, the stuff that reflects has its own physical characteristics and doesn't breathe or flex the same way the rest of the fabric does. There are more types than those, but it's the same problem.

And what makes reflective material effective, more than anything else, is surface area. So in order to have a large, visible reflective surface area, you have to cover a large area of a garment with a material that's heavier, less flexible or packable, doesn't stretch, and doesn't breathe basically at all.

Illuminite gets around that problem by applying lots of tiny spots of reflective stuff all over the surface, instead of concentrating it like a strip of reflective tape. So it will never be as bright, because by definition there just isn't much of it in any one place. However, it is good for outlining the shape of a body and it certainly is better than nothing.

But basically, surface area is what counts. Small reflective logos are nice, but not much; same for reflective piping. There's no substitute for surface area. That's why the reflective stripes on the tights near the ankles in that photo show up so much more than the Illuminite stuff on the jersey.

FWIW, you can buy fabric that has a reflective surface applied to the whole entire surface of it. But using it for large areas of a garment would be like wearing a plastic bag.