> Why are people in society B concerned with the majority working if they are unnecessary?

I think that's a great question to ask. Some possible answers:

A - to make money for the yacht class

B - to keep the 99% too busy/distracted to wonder why all the productivity gains of the last 50 years have gone to the yacht class (see graph above)

C - They're not even that concerned - they pay people to be concerned about that stuff on corporate media / in politics / in our Supreme Court.

The point above is that "100% employment" is absolutely not the barrier between society B and society A. There's no good reason for full employment to be "necessary" to a well functioning society.

It could even be argued that one measure of a functioning society is how many people need to work 60 hours a week just to have their basic needs met...