There are ways in which water and oil are similar. There are also analogies which are of little use. When you reach for a group “made up of human beings” as a similarity, you clinging on the latter.

Quote it as written: "organizations made up of human beings providing important services to the general public"; not merely "group made up of human beings."

An organization is more specific than a "group."

They both provide services to the general public, i.e. they are indiscriminant in who their clients are. This is different from, say, a corporate law firm that might decide to take just a handful of cases at a time and be selective about it.

And finally, their services are important, as in livelihood-saving. Of course, firefighters are sometimes life saving, so a better analogy would be firefighters working for agri-business, but "firefighters" still fits better than, say, "AMC theaters" because of the importance of the service offered.

Doctors is a better American analogy than firefighters