> I don't know about the United States of America, but in my country it's very common to do volunteer work.

Your business plan for America:

1. Live in an unknown country Z that's not the US, about which you don't know much.

2. Do volunteer work in Z, consisting of doing highly unknown stuff X for a secret number of minutes per year Y.

3. ...

4. Imply unknown profits for Z

5. The US implements a copy of the unknown volunteering in unknown country Z

6. ...

7. Imply enough unknown profits for the US to fix all of its unspecified problems.

Am I missing something, like known or unknown unknown?

What exactly is your problem? You could just ask, if you're genuinely curious.

Me neither, and same here.