If a family of 10 is increased by 1 member each year, that is an increase of 10%. You can apply a 10% increase in population each year, due to benefit seeking

If a family of 10 is increased by 1 member each year, that is an increase of 10%. You can apply a 10% increase in population each year, due to benefit seeking immigration, to a country. There is no "scale" issue here. And even if there was, the reasoning that followed can stand on its own (because the analogy was directed on the OP's analogy, and not on the reasoning provided).