If you read the article, one of the reasons the cost has gone up is supporting all the different bus colors because they have to keep 20 of same panel in different colors for different governments. If they had single color, then they could unlock better economies of scale.
I don't see any reason why it would need to be standardized to the same color in every city nationwide.
School buses are the only ones that do that because it's a safety issue as opposed to a convenience isuse.