Although what's funny about that, is in the "classic" 1973 (love that theme song) opening, they specifically say:
"In the Great Hall of Justice, there are assembled the World's
FOUR greatest Heroes"
Then only show (sitting around the team-table) and name: Superman, Wonder Woman, Batman, Aquaman (as the "four")
and then list "...those three Jr Super Friends Wendy, Marvin & Wonder Dog"
They count everyone (even the Dog) except Robin, pretty much an appendage of Batman, is not even listed as member. LOL!
In wasn't till the next 1977 season opening that they do name and show Batman
& Robin together, although still pretty much as one.
The next Challenge era, also seemed to count them as one, being classic 10 heroes vs. 13 villains.
Unless he's counted in the odd 11?
https://www.youtube.com/watch?v=o87EJkBQckE