The whisper of the soundtrack... I sense a selection bias here, even if the survey is formally completed.
An online survey on travel habits does not always capture the diversity of document verification behaviors, and it smells like respondent organization.
This pattern gives the impression that 75% of people plan everything in advance, but it could just reflect the propensity of organized people to respond to surveys.
To confirm this, a study with a more robust random sampling, such as random interviews at public administrations or airports, would be needed, rather than online forms.