The term black ice here often comes into play in conditions where exhaust will freeze on contact with the pavement. It's thin, invisible, and found at intersections where cars have been idling while waiting for lights to change. This is of course a problem when cars are trying to stop at said intersection.

Winter has all sorts of ways to make the roads slippery coupled with commute times occurring while it's dark. So yes, black ice is a danger, but so is freezing rain, or a thin layer of snow on top of old snow that has been compressed to ice. However, the biggest problem areas are intersections where cars are trying to turn or stop. As a cyclist you will know when road conditions are bad and you need to be extra vigilant, but it's not like cars are going to be randomly flying at you from all directions.

Overall, I'm much more bothered by cookie dough snow than I am ice but I will concede that cookie dough snow on top of ice is about the worst.