In 1900, the world struggled to feed its population of 2 billion. Most farming was still done by ox and horse drawn ploughs, in most countries. The exception, until the 1940s was Japan, where human beings ploughed the field, because there was not enough farmland in Japan, to feed both humans and cattle. James Michener portrays this poignantly in his novel, Sayanora.
The internal combustion engine, was invented in 1880s by Germans Rudolf Diesel, Nicholas von Otto, Karl Benz etc primarily powered cars. It was then adapted for use in tractors, bulldozers, harvesters and other machines for the farm. These replaced the oxen and horses as plough animals, dramatically increased the amount and speed at which land could be ploughed. Cars and buses, far more than railways, dramatically reduced the need for bullock carts and horses and horse-carriages. Two-thirds of farm output, was being used to feed these animals. This dramatically reduced the amount of food needed for those animals! Which is one more reason we are able to feed 7 billion people. Another was the Haber-Bosch process which revolutionized fertilizer manufacturing and use. This process continued with Norman Borlaug's green revolution in the 1960s and 70s.
Roads were built all over the world, cutting transport times from months to days and days to hours. This meant a government could prevent famines in entire districts or states, by transporting enough food in mere days.
When people, mainly well-meaning but ignorant environmentalists and a gullible pessimistic media, say that cars and coal-fired power plants are polluting the earth, and that pesticides are ruining farm, we must be aware that we’d starve without these technologies.