Cradling a sack of grain under one arm and a bag of eggs in the other, a stout woman leaves the open-air market and climbs into a horse-drawn taxi. The elderly driver, a smile creasing his weathered face, tugs on the reins and utters a sharp "Vamonos!" as the black carriage with a torn leather awning rolls away. The scene could have come from Cabbages and Kings, O. Henry's collection of picturesque short stories set in turn-of-the-century Central America. But this is no quaint, fictitious land. This is modern-day Nicaragua.
All across the country these days, horse-drawn, hand-pushed and pedal- powered...