Badges are designed to be different than reputation in a few ways, one of which is that they're meant to be pleasant surprises to many people. Much like achievements, as mentioned by jadarnel27 in another answer. Yes, you can look up how to get them, but unlike rep, where we really want all new users to understand how to earn it, badges are designed to usually elicit more of a:
Oh, I got a badge for doing that? Cool!
But here's the direct answer to your question:
Many badges are awarded for behaviors that are desirable, but shouldn't, in and of themselves, get you the privileges that high-rep users get, because they don't indicate the same trustworthitude as getting upvotes on content.
You wouldn't want to grant editing or closure power to someone who's not getting upvotes on questions or answers, but has tons of badges in things like upvoted comments (which are sometimes more funny than helpful), retags (which aren't always helpful), consecutive visits (which don't reflect expertise), etc.
Plus, if badges unlocked privileges, you'd likely see more grinding for them in undesirable ways, like people linking to their posts indiscriminately to get the page view-based ones, etc.