It is possible to register with Apple without giving them debit/credit card details. You can skip that part of the registration process. However, part of Apple’s security infrastructure depends on the user only buying safe apps from them. At some stage you will want to download an app from the app store. If it is an app that you need to pay for (say you want to learn a language), you want to buy music or for iCloud storage, somehow, you have to pay for it. A cheque in the post is no use to Apple. So you need to store your card details with them. Many manage without buying anything from Apple but there is some useful, fairly inexpensive stuff available.
In order to ensure you don't register a bank card with Apple, skip the card details on registration but, once registered, go to the app store and download a free app. You will be asked again to enter debit/credit card details but there will be an option not to register one and you can select that. It is the only time you get that option. If you decide to make purchases at any time, you will need to add your card details to your Apple account.