Display all posts for taxonomy term across multiple custom post types

You can do this with an array of post types and a tax query for your term. The question you linked had special requirements as only one of the post types used the taxonomy.

$args = array(
    'post_type' => array( 'books', 'movies', 'shows' ),
    'posts_per_page' => -1,
    'tax_query' => array(
        array(
            'taxonomy' => 'status',
            'field' => 'slug',
            'terms' => 'wishlist'
        )
    )
);
$wishlist = new WP_Query( $args );