Keep in mind though, this transaction was nearly instantaneous. Bank Wire transfers take 3-4 days to complete (at least, as far as I know with normal-person quantities of money). Instant international money transfer is amazing!
Fedwire and other real time gross settlement services (RTGS) are almost instantaneous.
SWIFT transfers usually are not: SWIFT is a way to communicate messages about transfers between banks, but they would still need a way to do the actual settlement. This could be very fast in the case of two large banks in different countries: if you are a customer in bank A, which has a correspondent account with B, and the recipient is also a customer with bank B. Then bank A can use SWIFT to say “please transfer $1 trillion from our account to the recipient’s account”, and that could happen instantly. (It usually doesn’t.)
But if the final recipient is actually a customer at bank C, then the money needs to get from B to C somehow. That could happen in the recipient country’s RTGS—Fedwire if it’s the United States—but it might also be slower, through ACH or an equivalent.
One problem with fast transfers is that many banks don’t have straight through processing for RTGS. This means that the money can get instantly from bank A to bank B, but may not get posted to the recipient’s account with bank B until a clerk gets around to verifying and booking the transaction.
My guess is the previous commenter is in US. There's an excellent episode of the podcast "planet money" which addresses exactly this question, and which also explains why the system in the UK is much faster.
Not exactly. To be sure it isn't a double spend it needs to be part of the block chain at least six down from the most recent block generated. Each extra block on top of the block where your transaction exists is a confirmation. For smaller purchases, ie not $150 million worth it's near instantaneous.
Yeah, I would bet that credit card fraud with chargebacks is probably more likely than the double spend scenario so it would make sense for a company just not care about verifying.
