Im not an apologist for the Kims, indeed I view the DPRK as a sick stalinist theme park along the lines of Ceaucesus Romania, but with more torture and bloodshed ( but not as much as the RW press would make it out to be ) - they were chums in the '70s - but the activities of the christian groups who take in defectors are a little suspect and I know that many of the ex DPRK citizens they shelter are prompted and scripted to say whatever they are told - and are quiote happy to do this - its pragmatism after all & anything is better than being sent back to NK and the inevitable shit storm they would find themselves in. Citizens are aware of the pecking order & entire family lines are blacklisted due to the bogus activities of some long dead ancestor - the DPRK uses traditional Korean "face" & heirachy conventions to keep a lid on things, rather than mass murder and massive concentration camps.Still shitty though.
With regard to the black market - its more of a Kim family business - they do take a slice of these unoffial activities & they do not happen without tacit approval of the family & their regional govenors - KYI is a fanatical micromanager ( or was until his recent stroke ) and oversees pretty much every economic & social decision personally - hence the chaotic economy and the steel plants that produce such low grade steel , that is is pretty much unsaleable.
Stand in the middle of the bridge on the northern border, looking back towards NK and the enforced darkness of the towns vs the neon of the Chinese side is pretty shocking
The chinese are pivotal in keeping the regime in place & true to form, it is used as a buffer, but also as a little bit of needling antagonism to the rest of the regions & indeed the USA