They've sure come a long way... we used to use our old chain driven potato harvester to dig up carrots after a slight modification. With potatoes sitting in a hill and the tops killed with spray before you harvest, it's a little easier as the front blade just cuts through the hill and you sift out the taters with a series of metal belts and a shaker tray, with one or two folks standing on the sideboards tossing out the rocks, dead animals and rotten ones. To do the carrots, we welded a modified ridging plough blade ahead of the scoop to break the land and free up the carrots, and up the conveyor they'd come. Had to move along a bit slower because the tops sometimes got snagged or bunched, but it worked pretty well, and was easier on the back. The potato harvester we had was built in 1928, lots of cast iron parts but held together for at least 46 years.