Why was the word ‘school’ covered up on these buses?

Q. Hello Honk. Yesterday I drove by a Knott’s Berry Farm parking lot, and there was a sea of yellow school buses. What caught my eye was that some of them had the word “SCHOOL” covered up on the buses. And some did not. I see this each summer. What is the rule about this?
Mario Luna, Anaheim
A. Good day, Mario.
School buses aren’t supposed to go more than 55 mph on the freeway or go into the carpool lane, said Officer Tino Olivera, a spokesman for the