Plating is just like paint, it is a thin protective coating. Obviously some platters are more conscientious than others. My experience tells me that results as a lot to do with part preparation prior to plating. This is what is time consuming and affect final cost. Most platter will strip parts in a acid solution prior to plating. Pitting/gouges will still be visible so some part need to be polished prior to platting.

https://board.moparts.org/ubbthreads/ubbt...tml#Post2013296