its all connected through markets. The farmers eat lunch at a deli, they don't eat lunch at a special "farmers only" deli. The gps they use to track the location of machinery in a field is made by a gps company that makes gps boards for hikers, boaters, etc., not a special farmers only gps. All of these things are interconnected through the market and that's what makes it so much less expensive. The 1% of agricultural workers rely on the contributions of the other 40-80% of workers because those other workers are all relying on each other to support their efforts in a complex emergent web of dependencies that are managed through (mostly) voluntary market relations.
Iceland is 81.8% and South Africa is 41.7%, according to the table on the page.