What's cute is that much of the time when I pay for something it's instantly charged to my card - my account balance reflects the deducted money, whether it's been actually moved out to the other account or not. But if a merchant gives me a credit/refund, it can take several days for that to show up - some places will say "two billing cycles" (although they have no idea how long my billing cycle is - I presume they mean their own internal cycles).

Money already seems to be moved somewhat instantly, but only ever out of my accounts.

Bingo. This is why it smells like something fishy. Like the banks are trying to earn carry/float interest. And possibly the government is in bed with them, by adding some regulation to impose an artificial delay, to supposedly add safety/caution, but in reality to give the banks cover to earn more profit on this carry/float interest. This is my best thumbnail theory, anyway.

That's because the plastic card interchange works in real time and ACH does not. Even your charge cards have a delay, though. There's a difference between authorizing a purchase and capturing the funds. Once funds are captured there's still a batch settlement process that happens each day. So it's not really that big of a conspiracy; the players aren't even the same.

Agreed on auth/capture/settle - it's possible it could be different though, we just have an entrenched group of players that prefer the status quo.

It definitely could be different. That's why I'm working on FaceCash.