It seems that there is a lack of understanding about this simple law. If there is no median, you have to stop. If there is a median, you don’t have to stop. Still, everybody stops on roads with medians. I suppose it’s better to err on the side of caution and stop on a divided street or road, but you don’t have to. AFAIK, this is also true of emergency vehicles.
NB: This is the law in Texas. Your state may vary.