Most free trial subscriptions let you cancel but keep the subscription active through the trial period, Apple included. I normally cancel immediately so if I forget about the thing because I stopped using it my card doesn’t get charged. All these free trials require a card on file so they can just automatically start the subscription.

Apple doing this makes it more likely people will forget to cancel if they don’t care for the product and automatically start the subscription. At which point it is far harder to cancel/get your money back.