Decouple the flashy: the idea that age alone dictates document verification for travel, as if there were no concrete reality, is a bit simplistic.
A young person who has already missed a flight to Zanzibar because of an invalid passport will not wait until the last minute next time, regardless of age.
It's the financial impact of an unforeseen event, the real worries of international travel, that shape this behavior, not generic sociodemographic categories.
Here in Belgium, with all the administrative requirements for certain countries, it's the experienced and tangible risks that prove what drives people to anticipate.