"Oh, I am not a TV reporter" - why not "I am not the TV reporter" or "I am not TV reporter"?

Question

Why here they said "a" TV reporter" not "the" or even zero " TV reporter", Then she replied "a radio reporter"

Please help me understand these sentences.

Answer 1

The indefinite article a derives from the word one.

Do you work for the news?
Yes, I'm a reporter.

There are many news reporters in the world, and I am one of them. You are simply describing your job. I'm a reporter; I'm a baker, I'm an English teacher.

The same goes for "I am not a TV reporter": my job is not one of a TV reporter. I am a reporter, yes, but not a TV reporter.

The adjective "TV" does not make the noun "reporter" definite, just as the adjective "red" does not make the noun "ball" definite here:

This is a ball. This is not a red ball.

---

Sometimes, if the position or function is unique, we omit the indefinite article:

They elected me President of Russia.
They made me Captain of the team.

This does not work in the Scott/Heather example. A news company might have dozens of TV reporters, so it's not a unique role. Even if it has one reporter at this particular point in time, it might hire several new reporters tomorrow, and they will all work together. A country is unlikely to have several presidents at once.

---

Had the definite article been used, it might've implied that there's only one reporter in your news company. Here's an example:

Do you work for Moscow News?
Yes, I'm the reporter.
Gee, that must be a very small company! Only one reporter!

In another situation, the use of the definite article might imply that some particular reporter is being discussed, a reporter the first person knows about:

Do you work for Moscow News?
Yes, I'm the reporter you heard yesterday in the evening program about Maslenitsa celebrations.

I'm that particular reporter (whom you heard yesterday when you tuned in to Moscow News on the radio)

---

The situation gets interesting if both Heather and Scott know that there's only two reporters in a small news company: one TV reporter, one radio reporter.

1. Scott: Do you work at Los Gatos News? I know they have a couple of reporters: a TV and a radio reporter.
2. Heather: Yes, I do. I'm a reporter there.
3. Scott: Where's the camera?
4. Heather: Oh, I'm not a TV reporter. I'm a radio reporter.
5. Scott: Oh.

Here, Heather can use a on line 4. But she can use the on line 4 either:

4. Heather: Oh, I'm not the TV reporter. I'm the radio reporter.

If she uses the, then she implies "I'm not that sole TV reporter at Los Gatos News. I'm that sole radio reporter there". If she uses a, then she merely describes the type of her job.