Stolen items are fenced on eBay. The payment processors don't have an issue with actual crimes like theft but want to impose a moral code on legal behavior.

Be realistic, if I offer stolen set of fancy hubcaps or something (ie something potentially expensive but doesn't have a serial # like a computer) there's no real way to tell if it's legit or not. If I offer porn for sale and there's an anti-porn policy, they can just say 'welp this is porn to us.'

Like how would you distinguish between a stolen item and a used item without requiring people to keep every receipt for anything they ever buy? This is not an endorsement of their anti-porn policy, just observing that that it's easy for them to implement that in contrast to your theft example.

It’s not about morals, it’s about chargebacks. That’s why.

Then you charge a higher merchant fee.

They could do that. Or they could choose not to be involved in that sort of business.

Can you explain in more detail? I just don't see the analogy you're drawing here. People may sometimes fence stolen items on Ebay, but you're not allowed to, and payment processors would definitely cut them off if you were.

Maybe that people may sometimes post illegal porn on OnlyFans but you're not allowed to either?

User-traded goods on e-Bay are also much harder to verify facts about than goods from a brick-and-mortar shop. Doesn't seem to prevent e-Bay from operating.

Except "sexually oriented materials" are not the same thing as illegal goods. I was NOT talking about "sexually oriented materials".