Writing a topical review paper with co-author(s)
Who does the actual &quot;writing&quot; (i.e. putting pen to paper or fingers to keys) is actually immaterial. I've published with half a dozen people where everything was &quot;written&quot; by one person, since he is (by far) the best writer in the group. He chose the words and the sentence structure.  But the ideas came primarily from two other people and the rest of us contributed ideas from our own experience. The &quot;writer&quot; synthesized all of that into a nice expressive form. But without the rest of us he wouldn't have been able to do it.
Authorship is (or should be) about intellectual contributions, not physical manipulations of keyboards or even of experimental equipment.
At the other end of the scale, I've written books with major publishers and worked with a copy_editor who helped with some of my (occasionally!!) awkward syntax. In no such case would anyone expect that their contributions were authorship.