FD has to balance any AI improvement in interdiction with consequence combined with human interdictors, so keep that in mind.
took my trade python to open to try chllenge again getting past trade embargo at a well known route. Human wing interdicted and i got away, second human interdiction halfway to station also got away but lost shields and took light damage.
third interdiction by NPC slowed me down, took lot more dmg due to no shields left from human interdictions, and just barely got away. Final human interdiction just before reaching station killed me and my 8M insurance/cargo rebuy.
no complaints re the cost - i did it to be obstinate and see if i can get past the blockade. But when you factor both NPC and human interdiction in same system, buffing NPC interdiction AI too much would essentially move even more players into perma solo or private, something FD (however not successful at it) wants to avoid.
so i would consider the possibility that FD knows quite well how to beef up npc interdiction but just chooses not to. It doesnt have to be a 'they must not know how to do it' thing.