Let me ask you, how does someone engage in pvp piracy when 90% of the traders carrying valuable cargo are in solo? Piracy is supposed to be a cornerstone of the game, yet the game's own design discourages it. This idea would at least make it viable in a small region of the galaxy.
While the game design certainly does discourage piracy (especially PvP piracy), it's not the modes that are the problem, and if you had an "open only" system people wouldn't be going there in the sort of shieldless T-9 which might plausibly be piratable.
A well-built trade ship can survive the small time needed to high-wake out, long before its shields go or a hatchbreaker can attach (especially with a well-placed point defence). So no cargo for you.
You seem to be expecting that it would go like this:
Frontier: "We've set up a high-risk high-reward PvP trade area"
Trader: "Great, I'll take my shieldless T-9 laden with Void Opals there immediately."
and not like this:
Pirate: "Your cargo or your ... oh, they've high-waked out again"
More importantly, the economics of piracy don't actually work very well anyway [0] in a game like Elite Dangerous. (Warning: maths ahead, feel free to just take my word for it that piracy is not economically plausible and skip to the end)
Trader: buys a hold full of goods for B, sells them for S (> B, of course)
Pirate: pirates goods for 'free' [1], sells them for the same unit price as the trader.
On an average trade trip, the trader has fraction P of their cargo stolen by pirates. (Sometimes more, sometimes none because they get through safely, of course)
Trader: profit is S*(1-P) - B
Pirate: profit is P*S
The pirate needs to make more profit than the trader from the encounters, or everyone just trades instead (or murders, because they hate traders and don't need the money)
So: P*S > S*(1-P) - B
So: P*S > S - P*S - B
So: P > 1 - P - B/S
So: 2P > 1 - B/S
So: P > (1 - B/S) / 2
But also, the traders need to make some profit [2], or they won't trade, and then there's no-one to pirate.
So: S(1-P) > B
So: S - S*P > B
So: S - B > S*P
So: (S - B)/S > P
Let's put some numbers in:
Palladium is bought for 12.5k, sold for 14.5k, so the pirates must steal at least 7% of the cargo (or they make less than the traders do), but they can't steal more than 13% of the cargo (or the traders make a loss on average and stop trading)
Military Grade Fabrics in ideal BGS circumstances are bought for 0.5k, sold for 10k, so the pirates must steal at least 48% of the cargo (or the traders make more money) but they can't steal more than 95% or the traders make a loss.
In the case of Palladium, the pirates need to be tuning their activity in a ridiculously narrow range to keep things sustainable - and even then, some traders will be unlucky or unskilled and get robbed more, and decide they can make better profits elsewhere. Also note: when the bounty hunters start coming after the pirates, the 7% the pirates need to steal goes up (to cover the costs of being hunted), but the 13% ceiling doesn't change. So if the bounty hunters are also making decent money by costing the pirates some rebuys, there might be no actual stable value at all.
In the case of Military Grade Fabrics, the range is much bigger - 48% to 95%. Keeping this sustainable, even when bounty hunters are added in, should actually be practical. Traders expect to lose a lot of cargo to piracy, but are making a high enough profit/ton to cope with that. On the other hand for the pirates to get up to 48% cargo stolen they either need to:
- successfully intercept every single trade ship and steal at least half its cargo
- steal basically all the cargo from at least half the trade ships (bearing in mind that a pirate ship is going to need more combat power than the trader it attacks, where exactly are you going to fit that cargo anyway?)
Even leaving aside the slowness of transferring hundreds of barrels between ships, and even assuming it's a perfect situation for the pirate where the trader is intimidated into handing over cargo without a fight, these are highly implausible circumstances. Better piracy tools for actually transferring the cargo would help, but that sort of near-perfect interception rate is implausible anyway, especially if you have bounty hunters escorting the traders as a way of finding their targets.
In neither the low-margin nor the high-margin case does it seem particularly plausible that both traders and pirates can be economically viable, and that's without even trying to give the bounty hunters a share of the action and model their costs, incomes, etc.
[0] Assuming here that people go into either trading or piracy for money nowadays. But you seem convinced that high trade profits will attract people to your pirate haven, so let's assume that both traders and pirates actually need the money.
[1] Lets ignore the marginal costs of limpets, ammunition, etc. Also ignoring the costs of being attacked by bounty hunters, to keep things simple ... and ignoring the black market's price penalty on the grounds it only makes things worse.
[2] Ignoring, here, the fact that they could make a guaranteed income elsewhere in the game with no risk, so the "ceiling" is actually lower ... and also ignoring for simplicity any repair or consumables costs incurred by the trader.
Piracy may be supposed to be a cornerstone of the game, but going right back to Elite I it was always something for the NPCs to attempt to do to the player as an excuse for shooting at them (and, fine, it still works okay for
that in Elite Dangerous). It was never a particularly plausible thing for the player to do, even to NPCs, and it works particularly badly if both the pirate and trader actually have to care about their budget.
The modes are basically a complete irrelevance - they'd have to rewrite the combat, outfitting and economic models from scratch to make PvP piracy work.