Out of all the deaths in a country, what share fall in each band of age? In the poorest countries the curve is bimodal — a spike in infancy, then old age. In the richest it's a single late hump. Pick two countries and watch the shape change.
182 countries with a full life table · source: WHO Global Health Observatory (Global Health Estimates 2021) · the synthetic-cohort death distribution, which removes the effect of population size and age structure so countries compare fairly.