This is an American thing in general, not just a workplace thing. I know that people in other cultures find it quite strange sometimes, and frankly it is when the actual meaning of the words is considered and what their use implies. But it has somehow just become a kind of standard default greeting.

I think it's probably meant to imply a kind of warmness to the person it is directed to, kind of like, "nice to see you," or "I wish you well."

No one expects it to lead to extended conversation when it is used nonchalantly like this. And you're right, it is frequently encountered in situations where one or both parties are in motion. Often in a form like:

A: Hi

B: Hi, how are you?

or

A:Hi

B:Hi, how are you?

A:Good, thanks!

or

A:Hi

B:Hi, how are you?

A:smile, nod

or

A:Hi

B:Hi, how are you?

A:Good, and you?

B:Good, thanks.

I think this is fairly common in languages, that words are used in a way that from their literal meanings you wouldn't expect. Idioms of course, but I think in other ways as well.