Let's strip away the media hype about age segments: the actual behavior of document verification has nothing to do with abstract demographic categories.
What matters are the practical consequences: missing a flight at Zaventem or being blocked at the French customs, that makes you move.
A Belgian who has already had a expired passport will not see their way of verifying papers change with age, but with the concrete fear of trouble.
The actual cash flow does not change with a nice age infographic; it is the administrative rules and loss of time/money that drive action.