Do you not have to show ID if a police officer asks you? Genuine question.
I thought you do have to show it if not doing so would prevent the officer from performing a duty related to potential criminal activity?
What? I don't get why someone would not show ID if they have one.
You don't have to. It's your right not to show your ID. You have the right to remain silent and also to ask if you're free to leave if you're not being detained.
https://www.aclu.org/drug-law-refor...acial-justice/know-your-rights-what-do-if-you
http://www.flexyourrights.org/faqs/when-can-police-ask-for-id/
Some states have laws where you have to identify yourself, but only if you're detained (reasonable suspicion that you committed a crime). California is not one of those states.
http://en.wikipedia.org/wiki/Stop_and_identify_statutes

There are lots of reasons not to show your ID. Hypothetically: If you're Mexican-American in Arizona, for example, I imagine it might be irritating and insulting to be stopped for being Mexican and to be asked to prove you're a citizen. This was a huge thing recently with the "papers please" laws Arizona tried to pass.
In this case, Daniele Watts had no reason to provide her identity, as she was doing nothing wrong and simply living her life like a normal person.