Why do money transfers take so long?

Question

Why do money transfers between banks take so long?

I transferred money from my bank to pay a bill online and it says it will be delivered in 4 days?
Why does it take 4 days to send money from one bank to another online?

Shouldn't money transfers and online bill pay be instant?

Answer 1

Money transfers take a long time because there's actually a human involved in the process.

The human actually processes the transfer for security reasons so that they can spot any fraudulent activity if there is any.