Answered well, and if you listen to the answer properly, this question will tell you how someone overcomes obstacles and handles adversity.
Only in the specific (and almost certainly relatively narrow) context of the time and place in which the achievement occurred. The question is, at best, a vague and inaccurate heuristic measure of the thing you note. The answer to it, and follow-on questions, may have little or no bearing on the position the candidate is interviewing for.
This question belongs on a country club application not on tech job application. Tech industry is one of last few places in america where one can hope to turn things around in life. Become great by getting exposure to new ideas and new memes.
'what is your most significant accomplishment to date' is much more telling.
pg is not hiring for a role, tho. he is trying to assess determination for a particularly difficult lifestyle choice - starting a company
How classist of you. There are plenty of people from working class backgrounds who achieved great things. Just because you started in poverty doesn't mean that you've never achieved something worth talking about in response to an interview question like this.
Honestly, I think disadvantaged people are in some ways at an advantage here--we have so many more limitations, that we have to become quite creative in our attempts to get around them. The more advantaged people can take a more convergent path because there are fewer obstacles in their way necessitating an annoying (but ultimately educational) detour.