Say what you will about the built in WordPress search functionality – sure, it could stand to be improved (personally I’m a fan of SearchWP) – but not all projects warrant the same requirements, right?
Sometimes, the built-in search functionality works just fine out-of-the-box. It gets a little more involved if you start introducing, say, custom taxonomies or custom post types, though.
That is, say you’re working on a project or have a client who needs help with modifying the built in search functionality so that it allows for searching custom post types. There’s actually a lot of flexibility provided in how you tailor the search results, but for this case it’s pretty easy.