Could you elaborate on why that seems reasonable to you? The airline will already have my passport and credit card details, home address and mobile number. In my opinion, it should be the user's choice whether they create an account or not.
Your demand boils down to having less options to do actions with the business. Options that already exist and come out of the box.
Having an account is not as scary once you realize what it is and what it represents.
No, I’m requesting, or demanding if you prefer, the choice. An account is a user convenience, not a business necessity. I’m asking why it is reasonable to force customers to create an account to book a flight?