Re: Dangerous toys...
(No, I haven't driven JD. It was IH and Ford.) The equipment I used didn't require advanced tools to be fixed, and some of the equipment was, in fact, welded up from scratch. A couple of the tractors were new almost 20 years before I was born, and they were still going strong.
Repair.org has a relevant article about this topic. Read down to the part where it mentions the $100K+ transplanters sitting idle.
There's things that I can appreciate needing a technician, and then there's things that many people can do with diagnostic equipment and not-so-advanced tools. I simply view it that the manufacturers should not have a total lock on repairing the equipment. Farms are infamous for the injuries people sustain there, so I can appreciate the concern for liability. However, the vast majority of the injuries come from equipment that is operating properly.
The local papers have also had various articles on the same problem. Equipment with simple problems can't be repaired locally. Not advanced problems, simple things that can be remedied without advanced tools.
Since farms are businesses, at some point the operating cost of a problematic piece of equipment means that it's going to be sitting idle, and that means money down the drain. And if money keeps going down the drain, then the farm goes out of business.
(Everybody else) Combines: Typically individual farmers don't own large combines. The combines are owned by combining crews, who come in and cut the wheat when it's ready. So when these break down, yes, it's a lot of money for them, and a big dent in their schedule.