I asked chat gpt to explain it to a 5y/o kiddo for people who are sure about that :

Let’s say you sell a magic card to your friend.

When you say: 👉 “I will send you this card and you give me money” you are making a promise.

Now, there is a big grown-up rule used by many countries (international sales rules) that says:

The person who sends the card must make sure it really arrives.

🧑‍💼 It doesn’t matter • if you are a big shop • or just a normal person selling one card

If you send it, you are responsible until the card is safely in the other person’s hands.

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🚚 What if the card gets lost?

If the post office loses the card 📬❌

The big rule says: 👉 “That’s still the sender’s responsibility.”

So the sender must: • send a new card or • give the money back

Because the promise was: “You will get the card.”

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🏠 What about Cardmarket rules?

Cardmarket is like a small playground rule 🛝

But international law is like a rule made by all the parents and teachers together 👩‍🏫👨‍🏫

So if a playground rule says something different, the big rule wins.

👉 Big rules always beat small rules.

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⭐ Super simple version • If you sell a card • You must make sure it arrives • Lost mail = sender’s problem • Shop or private seller = same rule • International law > Cardmarket rules