Its not "everything". You can dead reckon a lot of stuff on newer tractors.
But the problem is everything has a module on it. So even if you do the work yourself to replace the turbo on your 4930, you still gotta pay a "tech" to come out with his laptop and tell the machine its ok to use that turbo.
True, but there are 2 caveats:
1. If you pay for a subscription you can access a lot of dealer functions, at very least for diagnosis (as I understand it, with the green version you are locked out of changing anything emissions related, but short of that you can do almost anything a dealer can), if you have a couple million in any one color iron and a couple of full time shop guys you likely have a subscription.
2. When you can call the dealership service manager and say "we need a tech here with a laptop after X time tomorrow to program the new turbo we bought from you today" you are more likely to get someone (just need someone with a laptop and wheels) vs "I need someone come out and fix my tractor that will start but has no power" (which would require a full service truck, diagnosis, etc) ESPECIALLY in the busy season.
Such discussions go much better when you spend a couple hundred thousand a year at said dealership.
Also, on equipment the size of Big Bud, odds are really good that it will get fixed on site vs hauling it to a shop for most anything short of an engine rebuild no matter who is fixing it (and even on an engine rebuild, it may get pulled, rebuilt in the shop and brought back to be installed).
If it's a Cat engine/transmission like someone said , they would likely have a Cat dealer come out if it needs a dealer to work on it.
A local large orchard near me has a 4 row tree planter (has 4 guys riding it who plant a 6-8' tall "bare root" fruit tree every x feet) that they pull behind a large tracked tractor. The controls guy at work setup a PLC for it that reads a wheel speed sensor on the planter and it tells them when to plant a tree.
The tractor has GPS and some kind of input from the PLC so when they plant a tree, it also marks the location of all 4 trees in the GPS map of the field.
Something like this, but 4 rows instead of 2:
Aaron Z