A COA is normally only needed on high end items. So for example you may find it with a vinyl caped Jawa, or rare foreign item - For example the burgundy Bib Fortuna. In these circumstances a COA from a grading company may also be supplemented with a COA from a well known Lily Ledy collector and authority on the subject such as Özio (Horacio Narvaez) for example.
I would certainly not expect it with lower value items up to and including the R2 pop-up saber. I would rightly or wrongly assume that the grading company know enough about the common items to not of made a mistake (though even they are not infallible) :lol:
I have not seen a COA with an R2 pop-up. Others may have though.