> pre-authorization

If you need pre-authorization use credit, iDeal is a debit system.

> It hands over the customer's IBAN

SEPA Direct Debit requires my consent one time on my banking app.

Giving out your IBAN number is generally safer then giving out your Credit card number, date of expiration and cvv code.

Additionally it allows for things like name to account checking, therefore making it less likely you will be scammed.