I'm aware that, mechanically speaking, people smuggling stuff into my colonies is half the time a GOOD thing for me, it increases accessibility.
On the other hand, I don't always want them to, and yet when I catch a smuggler there doesn't seem to be any option to say "You're in my space, submit to a cargo inspection or die" the way the main factions do.
Why not? What if I'd rather they didn't smuggle in all sorts of random bits? Indeed, there aren't really any special interactions for flying around in space you control with your transponder on, and I think more of that would be good.
(I did find it amusing my own fleet ran from me... because I had my transponder off. That was funny, and mildly embarrassing.)