I have two hypotheses.

First, France already had negative demographic trends during the Napoleonic era. That might help explain why Macron’s call for a “demographic rearmament” is not necessarily taboo today. France started experiencing smaller family sizes quite a long time ago, so the current demographic numbers are partly a reflection of past trends rather than the situation today. In a few years, Italy will probably face an even worse situation.

Second, in some countries, the very high number of elderly people may partly be the result of inaccurate population records. Some countries have a combination of incentives for elderly people and demographic records that were badly damaged during WWII. This may have made it relatively easy for someone to claim that they were, for example, their grandmother and receive benefits. Decades later, some of these people are supposedly over 100 years old.

There is even an Ig Nobel Prize associated with research into this phenomenon.