In terms of the REFUND process; this works the same as it does today. No one returns to the seller and says "UNDO my transaction," they say "It doesn't work, I want a refund." It's a NEW transaction (just ask the sellers bank or ERP system); These scenarios are easily handled in blockchain
That's not true. I ask for a refund, the seller says no. I compain to my credit-card provider, they reverse the transaction and give me back my money. They then either get it back from the seller or commence legal proceedings.
Again, the average customer can't do that with Cryptocurrency. All sales are final. No refunds. No exceptions.
Try sending funds from South Africa to Mexico and see how long it takes, and how much it costs.
https://transferwise.com/pricing/ Quicker and cheaper than Bitcoin. Much easier to use as well.