If you want somebody to proof something carefully, make sure they think they’re the only person who will see it before publication. If you don’t want them to read it at all, include half the company when you ask for their input. There’s plenty of research on this* but the graph says it all.

* Latané & Darley, 1968 is the classic study, but you may find the Wikipedia articles on the Bystander Effect, Pluralistic Ignorance and Diffusion of Responsibility give a better overview of the work people have done on this.