Apple Cash offers two tiers of service for transfers. The free method takes one to three business days and transfers over the ACH network. The instant service to a verified debit card has a fee of 1.5% of the transfer amount. The rate may have changed 1/4% or something, but the fee has always been charged for instant transfer.
Person To Person (P2P) transfer are transfers from one Apple Cash account to another Apple Cash account. This service is free and may be what is confusing you.
https://applecash.greendot.com/termsconditions/