pt2 - sorry I stuffed up.

4. B gives the code to his local broker, pays a fee and collects the sats.

5. The transaction is informally recorded by both brokers and the debt is settled later, through various means such as cash, goods, services etc

without a direct money transfer .

6. Its fast, and fees need to be low, to make this work.

Fun fact -

Hawala is still practiced today from Persian times. Western countries outlawed it.

And it works with offline networks.

The gatekeepers are the brokers - I don't have an answer for this.

Perhaps someone else like Lyn Alden can give us a clue.