Why you have to wait five days to receive an auth code for gTLDs?

The current administrative contact has been notified of your request to transfer the domain name away (FOA). They have 5 days to decline the transfer. If no action is taken within this period, the auth code will be sent to the account owner's email address, and the domain will be unlocked on the 5th day following the transfer request.

This process is fully automated. Please note that any manual intervention in the transfer out process may incur additional charges.

For more details, refer to ICANN regulations at the following link: https://www.icann.org/resources/pages/policy-2012-03-07-en