Based on your financial expertise, provide your response or viewpoint on the given financial question or topic. The response format is open.

Why are bank transactions not instant?
It is a rather complex system, but here is a rough summary. Interbank tranfers ultimately require a transfer of reserves at the central bank. As a concrete example, the bank of england system is the rtgs. Only the clearing banks and similar (e.g. bacs) have access to rtgs. You can send a chaps payment fairly quickly, but that costs. Chaps immediately triggers an rtgs transfer once the sending bank agrees and so you can be certain that the money is being paid.  Hence its use for large amounts. Bacs also sits on the rtgs but to keep costs down it batches tranfers up. Because we are talking about bank reserve movements, checks have to be in place and that can take time. Furthermore the potential for fraud is higher than chaps since these are aggregrated transactions a layer removed, so a delay reduces the chance of payment failing after apparently being sent. Faster payments is a new product by bacs that speeds up the bacs process by doing a number of transfers per day. Hence the two hour clearing. For safety it can only be used for up to 10k. Second tier banks will hold accounts with clearing banks so they are another step down. Foreign currency transfers require the foreign Central Bank reserve somewhere, and so must be mediated by at least one clearing bank in that country. Different countries are at different stages in their technology.  Uk clearing is 2h standard now but US is a little behind I believe.  Much of Europe is speeding up. Rather like bitcoin clearing, you have a choice between speed and safety. If you wait you are more certain the transaction is sound and have more time to bust the transfer.