Learn English – Why are fishermen(women) referred to as ‘Anglers’

It's an amusing point. As others have noted, in the computer industry the "customer" and the "user" are often not the same person, so we need different terms for them. Of course this is true of many other industries, too. But I think most other industries have more specific words. The person who buys a car is generally referred to as a "customer", but anyone who uses it is called a "driver". Likewise in the publishing industry someone who buys a book or magazine is a "customer", but someone who uses the book is a "reader". The appliance industry does talk about "appliance users". Maybe there are other cases.

Maybe the distinction is more pronounced in the computer business because customers and users are more distinct than in most industries. The customer is usually upper management; the users are usually clerical workers. Well, I suppose you could say the same about many products that are typically sold to businesses. Like, the person who buys a forklift truck probably isn't the person who drives it.

I think this is more an "additional musing" than an "answer". Whatever.

If you look at the entry for flora at dictionary.com you can see:

flora noun — 4. the aggregate of bacteria, fungi, and other microorganisms normally occurring on or in the bodies of humans and other animals: intestinal flora.

Furthermore, if you look at the entry at etymonline you can see this:

extended form of *bhel- (3) "to thrive, bloom,"

Which is talking about the PIE root. It seems appropriate to use flora to refer to fungi, bacteria, algae, etc., because they all bloom and *bhel- is the origin of the word bloom.

English speaking scientists will often take words from English, especially ones with a Latin or a Greek base, and use them for what seems appropriate at the time. Sometimes the scientific meaning comes back into the mainstream. E.g. orbit, torus, virus, etc.