Chile is one of the richest countries in the region. Haiti is the poorest. Ecuador has a centrist government. Bolivia's is socialist.

Yet, from Port-au-Prince to Santiago, furious demonstrators were marching this week to demand fundamental change, part of a wave of often-violent protests that has set tires, government offices, trains and metro stations ablaze across Latin America and the Caribbean.

What's driving the protests thousands of miles apart, across countries with profoundly different politics, economies, cultures and histories? One important factor: Despite their differences, the cou...