Listen up. When the customer spends on the cartel, the offchain transaction would happen at that point. So the Bitcoin blockchain still shows the customer owning the coins.
Why do I still own these coins if I have spent them?
cartels might prefer to not send the transaction to the Bitcoin blockchain
ever. And keep them offchain. Did you get it now?
P.S. I don't think they would choose that strategy, so please stop cluttering this thread with this off-topic discussion on not understanding the Bitcoin technology and terminology (e.g. offchain). If you still don't understand, please send me a PM and I will explain there. I am not angry, I appreciate your posts, but please in PM so I can explain without burdening the thread okay.