Follow the incentive: who really benefits from the idea that age dictates the travel document verification behavior?
It is an oversimplification to believe that our administrative habits are reduced to our birth date rather than to actual constraints and responsibilities.
In Belgium, no one checks their papers in advance for fun, but rather out of fear of the logistical nightmare of missing a flight or a compromised event, regardless of age.
A thirty-year-old couple with children will be much more motivated to prepare months in advance than a seventy-year-old person without family responsibilities, because the stakes are different.
The cost of an unforeseen event is the real driver, not an age category. For example, if you organize a wedding and guests miss their flights due to unverified documents, the emotional and financial cost is enormous.