Was talking to my step dad yesterday and he mentioned he remembers, as a little kid, helping out at Pakulis' farm harvesting outs with an old combine that filled bags. Now that's old.
This isn't a combine -- the part the workers are tossing in the bound bundles is a thresher which seperates grain (oats) from the stems (which becomes straw). Before combination harvester threshers, grain would be harvested by a "grain binder" that cut and bound it into bundles then stacked in shocks to protect them from rain in the field until later brought to the thresher.
Straw used to be kept outside in stacks, just like you would have hay stacks. Hay and straw, properly done, is sheds water remarkably well -- think of thatched roofs. The straw chute on the thresher is long and high to facilitate making outdoor stacks.
As we got into the 20th century balloon frame construction allowed larger hay lofts in barns which allowed a lot of loose hay to be stored inside -- where it you had even less loss, and better yet could use gravity to toss it down to the animals instead of hauling it inside.
Another trend was the development of Hay Presses -- early stationary balers. These balers allowed hay and straw to be compressed into easily shipped bales for transport into our horse-powered cities.
With farms increasing in size -- both in acreage as well as the volume of crops grown per acreage with improved research, education, fertilizers, pesticides, and varieties -- farmers would increasingly use baling on their own farms. You could store more crops inside in the compressed form, and it's easier to handle and trade. In the above video, the straw is being fed by a funnel directly into a stationary baler -- today's field balers would come later.
The oat grain is the animal feed -- that's what the two youngsters in the grain wagon are making sure gets distributed well in the wagon. That will be emptied into a mouse-proof grain bin later. Straw is the by-product used as bedding, able to absorb two or three times it's volume in water and urine. This is different from hay which is cut as animal feed and harvested at a stage when nutrition comes from both the developing seeds as well as the leafy stems.
Going from older technology that would be quite familiar to a typical 1930s farmer, let's look at Glenvar Farms in Australia using state of the art combines along with their own system they've developed to bale as they go:
Many years ago a farmer friend of mine gave the sage advice it's not what you gross, it's what you net. The Amish have the labor pool to use the older technology, and I have no doubt net much more per acre by not having large loan payments to make. In many areas though labor -- particulary for seasonal activities like planting and harvesting -- is the scarce resource and requires the use of efficient but expensive machines.