The raiding quests that require marines are very hit and miss. Raiding soft targets pays well for how fast the player can do them (right there in the core) and its not hard to go transponder off to some worlds. Others that want hundreds or thousands of marines at major worlds with patrols... yeah not so much.
It my case, my raid target was soft and easy to raid (no problem for my 200 or so marines I haul around for opportunistic raiding). My gripe was with the revenge fleet afterwards. After seeing that, I think "raid equals disguised intel bounty with less reward", and have avoided raid missions ever since because I do not want to fight a bounty fleet for nothing. Makes me feel like a sucker taking the job (and me thinking the client wanted a hit job on a fleet but offered it as a raid instead so he can pay less money for the job). If I want to bounty hunt, I should look at intel for bounties and hunt them, not fight revenge stalkers after doing seemingly easy odd jobs.
1) All black market trade requires transponder off or free port.
2) More patrols at minor ports.
3) After a few trades pirates "learn" that the player is smuggling lots of high value cargo, and start laying ambushes for them. Not quite revenge fleets in terms of relentless chasing, but lying in wait along the buy/sell trade route the player is using or at common destinations (Chalcedon for example). As the player ramps up their smuggling into the hundreds of thousands of millions, major factions take notice. Shipping hundreds of tons of heavy armaments (with no taxes!!!) is disruptive to sector stability after all...
I already do #1 always. I never ever want a non-zero chance of getting stopped by patrols, given the contraband I always haul around (AI cores, one of every item to see prices). I know that is not what many people do, but for me, this would be no change for me. If anything, no open trade allowed in black market stops me from accidentally selling something while transponder is on and I reload to undo that mistake. I like to preserve the "none" chance, and if I sell openly, I lose it and I can never get it back.
For #2, need to add hostile fleets in systems without patrols. Three of the core systems have no patrols whatsoever and the only threat are pirate fleets if the fleet is not big enough. Also, pop-up bases out in the fringe have black markets too.
In previous releases when pirate bases spawned in a system adjacent to my colony system, I visit them to sell a bunch of junk at their black market (and buy a few of theirs if I want), before I raid and steal some of it back, then blow them up to remove "Pirate Activity" from my colonies. After a while, they come back with more Pirate Activity. (Now, thanks to Piracy Respite, not my problem, unless they steal my sensor relays and mess with my slipstream map.)