Most farm jobs are not sitting in the tractor all day. There are only a few farms in the world where a tractor has someone sitting in it all day every day. Most farms the tractors are used for 80 hours a week just a couple weeks per year (planting and harvest time). The rest of the time the tractors sit in the shed. There is a lot of non-tractor jobs farmers do. Many of the farms where the tractor is used full time every day the tractor is just pulling the harvest wagon and the crops are harvested by hand - one person drives the tractor while 30 walk behind it harvesting the crops.

The autonomous tractors are for use in fields where there are no other humans (at least so far)