I know this isn't that relevant to your post, but I kind of think the evo-psych explanation for why people care about politics is really stupid.

Do you mean that this particular evo-psych explanation is really stupid? That I can understand, since it does include burdensome details and questionable, overly simple specific claims. But in general people's political instincts being explainable by evo-psych seems to be among the most obvious and least controversial applications.

Here's a better explanation:

• In America, if you do not vote, you're considered a bad person.

People in countries that are not the USA have similar political instincts to those in the USA. This includes countries like Australia where people are motivated to vote by legal obligation instead of shame and countries that aren't democracies at all so voting doesn't come into it. This explanation is not better. It is a specific explanation for a phenomenon that is more general. Even apart from this it strikes me as an implausible just so story.

Or here's another one: when something is on the news a lot, people will care about it even if it doesn't affect them at all and isn't really inherently interesting (the royal wedding, the Casey Anthony trial, celebrity gossip).

This strongly suggests to me that the bias towards spending time on politics has an evolutionary psychology cause. Interest in gossip about high status figures, shaming and criticising targets, calling for punishment, advocating policies for the distribution of resources and privileges and advocating people or groups as deserving of allegiance. It's all part of the monkey social hierarchy game.