Anyone who has read the last several pages of almost any NTSB Final Report will easily understand that this response by FAA is far from rare. FAA often ignores NTSB or makes endless excuses about why NTSB's suggestions cannot be implemented. It is also obvious that FAA Does NOT like being told what to do and NTSB has no authority to DO anything beyond investigate and report; obviously a cluster-f'ing mess, but also our law. Further, FAA often lacks budget bucks and it can take them a year or more to write/revise regulations that the Part 121 carriers must implement at their own expense. Personally, I often envy the nations that use one agency to cover both major functions. Why is this so in the U.S? Turf battles!