read it? is it worth a read?
it doesn’t seem to mention the two most obvious types
agents - people whose only job is intermediating, forwarding emails between a business and a customer, but not letting then talk directly. like employment agents who won’t reveal the name of the company, because they know you could just talk to each other directly: the agent knows he is useless.
police, military, bouncers - people who spend 99% of their time doing nothing, standing around on street corners. when they do anything, it is only to fight, beat or kill normal working/productive people.