The legitimacy of an enterprise shouldn't be judged based on where it's allowed to happen - it should be the other way around. The two app stores should be designated as 'slave markets' for allowing this to persist for so long after being alerted. It's especially ironic that these companies are keen on deep invasion of privacy of regular citizens in the name of CSAM and terrorism. This is an exaggerated form of their 'Rules for you, none for me' attitude.
In addition, I object to the 'black market' terminology. Unlike the objections these companies have with 'master' on git - which doesn't have any relationship to slavery, black is an actual term related to a race that's misappropriated with a derogatory connotation.