The drag or work required to snap the extractor claw over the casing base or case head is low compared to other operations, but for good or bad, that action occurs at a time that there is less energy available to provide that work, be it stored in spring energy or mass in motion. A properly manufactured extractor is required, its not the easiest to make this in this system and does not add much to the total work overall to operate in the system, but is required for proper function,
During the extraction and ejection events, the angles of the components come into play, the interface between them need to be in a balance that allows those angles to work in a harmony to deflect them out an opening that is not restricted otherwise, unless other considerations come up.
Most would not like to jump onto the extractor business due to the part complications for this system, neither would most shops not jump in on the ejector business, as those parts are more specialized. It is easier for a medium sized shop to strip a bolt and carrier and have those coated by a 3rd party.
It is not a question of potential gain with the smaller components like the extractor or ejector, there is a cost involved. Larger companies can do the QA/QC. The bottom line is if that is worth it overall to make a fruitable business or not?