What do admission committees look for in a diversity essay?
It seems to me that it would be prudent to start from the assumption that the words in the question have been chosen carefully, after some deliberation; and so she should answer the question put, as it is asked.
The quote you've given does not ask for complaints. It doesn't speak of judging her by national origin, ethnicity or financial status. It doesn't ask her to talk of struggle. So those things would only go in the answer if they give a particular perspective that adds to the value she would contribute to the diverse learning community they strive to create.
They want to know how her status as a member of a historically-under-represented community adds to the value she would contribute. In your answer, you've already given three aspects of that. I'll paraphrase slightly - I hope I haven't distorted your friend's intended meaning - and for each I'll frame it within the question as asked on the application form:
- she's seen her being from a historically under-represented community as a challenge rather than a struggle; as a member of the department her very presence could provide a positive role model for others both internal and external to the deparment
- she's maintained optimism and not let the status quo get her down; as a member of the department, she would bring a realistic optimism and determination.
- she's sought to work towards a system that rewards merit for its own sake regardless of national origin, ethnicity, financial status, and so on; as a member of the department, she would contribute to the department's culture of meritocracy: academia of all places should strive to overcome conscious and unconscious biases, and work strive towards meritocracy.
That would seem to me to cover the question on the form as it has been asked.
Yes, indeed, there are many ways that this discussion could get off-track...
The specific, relevant point is that many universities have certain pots of money ear-marked for whatever-it-is that "diversity" refers to, and "traditionally under-represented groups"' members are the only eligible competitors for any part of that money.
(The discussion of the sense of this is of course the elephant-in-the-room, but is irrelevant to the already-earmarked funds.)
That is, at this point, being a woman in a STEM field (Science, Tech, Engineering, Math), or of ethnic origin other than northwestern European..., or... opens certain money-pots to both the department and to the individual.
It is true that one might easily find reason to not go down that path, ... but I note that many people will presume that one has done so if one had the chance, and all that that might entail.
Honestly, if I were in that situation, and did not have severe need, I'd skip it, just to be able I'd skipped it. But maybe nobody'd listen...
I can clarify further, if this is to-the-point for the questioner. I've been involved with such stuff for a long time...
Edit: to clarify, for example, my department did not create the literal "diversity statement" component of the application, it was created somewhere in the central administration. That is, although we have tried to avoid traditional biases (e.g., ideas how "how a mathematician looks", and such, often included male-gender-correlated attributes that, arguably, have nothing to do with mathematics), we did not formalize any part of such discussion. We've tried to be unbiased for far longer than this recent appearance of overt statements about "diversity", not for any immediate tangible reward from higher-ups, but for more idealistic reasons. Having central administration throw a little money at the situation doesn't really change much.
The reason for the question may well depend on the School and its own reasons. One popular case of this is the University of Michigan. While the school may feel diversity is important, and through affirmative action it can achieve it, the government or voters may not agree. In this case, Michigan created an essay section for contribution to diversity, in which they can more actively decide admissions based on diversity when affirmative action is not available.
Answering the question honestly is the best policy. Of course you would not want to lie, as an interview would probably create automatic rejection. If you do not want to come off as 'complaining', dont complain, it doesnt ask that. Answer how your background can contribute, and the simplest of answers is what your question mentions:
As being a female immigrant from latin america, I have been considered a minority. However, I do not look at this like a struggle, I look at it as a challenge, and I think my mindset will help contribute to both diversity and academics at the University.