When I leave work, I do a right turn out of a side road, onto a main road, and since Octoberish, I've been doing this in the dark, or dusk.. There are often cyclists coming along, some lit, some not (and one last week lit by a flashing amber LED on the front....).
It's true, I see the lit ones sooner, but I see the unlit ones too, no matter what they are wearing. The reasons?
a) up here, we have these things called 'streetlights', which make it possible to see quite well at night
and
b) I look, look, and look again before I pull out. With some more looking as I go.
It is possible to miss a badly or non lit person until the last minute, esp with other lights behind them. But I suspect in about 90% of cases, it's down to people actually not looking properly. Like really properly. The difference between me and a driver I suppose, is that if I get it wrong, I get hurt, they just get a dent in their door.
That said, I carry two or three lights, and wear a yellow jacket - mostly so that in the event of SMIDSY I can say "And which bit could you NOT see?"