Today in the world we see a difference in parts of the world and we can map those areas in which people are involved primarily in subsistence agriculture as opposed to those involved in raising cash crops . To feed self and family. Some surplus might be sold but that is not the primary purpose. Agriculture products seldom sold directly to the consumer, instead they are sold to large food processing companies. People have been pushed away from farms because of the difficulty in making a living and pulled to other, more urban jobs that pay better.
Large size is partly the consequence of mechanization.
As the result of large size and mechanization, farming is a very expensive business. There are fewer farms and fewer farmers in the US but there is roughly the same amount of farmland since 1900. During the 1960's, population began growing faster than agricultural land expanded, especially in the Less Developed Countries. Many predicted mass starvation, but these predictions did not come true, because new agricultural practices have permitted farmers to achieve greater yields. It started in the 1950's with an intensive set of experiments to produce higher yield wheat.