Yellow students are still learning and as you have indicated in your response, the use of passing zones between 1 & 2 and 2 & 3 takes a bit more confidence than at other zones. That is why we had the classroom. To burden Yellow drivers with that added pressure makes no sense. We now put instructors in with Yellow graduates in White for that reason, to teach them the new passing zones and see how they handle the traffic.
As I tried to explain, the difference between White & Black is purely experience and ability. Why should there be any different rules from one to the other?
To clarify my comments about combining Black and Red, this only happened when we had very small numbers (maybe ten in each group on a Sunday afternoon) and it is not anticipated to be repeated anytime soon. Especially with the number of participants we get now at every event.