What are the social, economic, and political concerns for a country whose population is getting older/shrinking?

Why do governments supply public goods and services instead of selling them to those people who use them

Persons who have not yet attained the legal age of consent under the applicable laws in the jurisdiction in which the research was approved.persons who are under 18 years of age.persons who have not yet attained the legal age of consent under the applicable laws in the jurisdiction in which the research will be conducted.persons who are under 21 years of age.

Historical vs today's presidents (compare)