The most common color would be color of family car since school buses are rarely used in most of the world and even in some of those countries in linked article

The most common color would be color of family car since school buses are rarely used in most of the world and even in some of those countries in linked article like China seeing yellow school bus is rarity and in rural areas is much more common to see just some van of whatever color (grey, green, etc.) with bunch of benches in back and dozens of kids inside there travelling between villages. Article also doesn't really touches why we keep using yellow color (certainly not just because bunch of people hundred years ago decided on it without any scientific basis), it is better explained here without lengthy article. https://www.catrentalstore.com/en_US/blog/why-equipment-yellow.html https://www.catrentalstore.com/en_US/blog/why-equipment-yell...