I was going to write something but this was just easier to explain the authorization hold. https://en.m.wikipedia.org/wiki/Authorization_hold
As for refunds, the company (their bank etc) initializes the refund. I have no idea the company side but I do know financial institutions (depending on the size) run those credits to your account through a computer program that does large batches of refunds at once. Imagine having to credit accounts manually by verifying ledgers and depositing those monies into the correct account. It’s take forever to do what one program can do in minutes. They recieve the file, they refund the money in the next batch.
I had a retailer take money that they weren't supposed to and struggled for 2 and a half months the have it paid back. Perks of living in South Africa.
As for refunds, the company (their bank etc) initializes the refund. I have no idea the company side but I do know financial institutions (depending on the size) run those credits to your account through a computer program that does large batches of refunds at once. Imagine having to credit accounts manually by verifying ledgers and depositing those monies into the correct account. It’s take forever to do what one program can do in minutes. They recieve the file, they refund the money in the next batch.