Payments are immediate between countries too. On my vacation in Armenia (you know, former USSR and a pretty poor country) I paid in the supermarket with my Dutch debit card (chip with PIN), I immediately popped my phone and opened the banking app for my (small, Dutch local) bank, and it showed the withdrawal.
Australia, NZ, Singapore, most EU countries all have instant person-to-person transfers with little to no fees and supported via the government. 500 euro can be gone like that. Poof. But it's all within the same country. And when it's within the same country, it's traceable, reversible and enforceable by law.
So the 1-3 business days isn't where the protection is at. It's the way we mark and track transactions. The real danger, is SWIFT transfers. Once that money leaves the country, it's very unlikely you'll ever see it again.
[1]: http://penguindreams.org/blog/the-american-banking-system-is...