My feeling is that this survey on vacation planning does not tell us anything truly relevant about verifying identity documents.
It’s a pattern I sense, a "gut feeling", not a quantified fact, but which makes me think that administrative prudence is a separate matter.
A tenant in Spain knows they must verify their papers to avoid issues with bureaucracy, not because they "plan their vacations," it’s a ingrained habit.
If we specifically asked in the survey "When do you verify your NIE or passport for a trip?", the link would then be much more evident.