Re: "tended to use “templated or generic” reasons"
see also timesheets and travel authorisations etc.
Once the applicant has found a form of words that works, there is every incentive to use the "right answer" next time. The approver probably has many similar admin tasks, and may see their role as checking the form or process, not the truth or "proportionality" of the underlying facts behind it. That the form exists proves the applicant has thought about the matter , therefore due process has been done, therefore tick.
This research finding won't surprise anyone who has worked in a large organisation, I suspect. But good to have a study to conclusively prove it.