My theory is that Kubota is a Japanese company. Interest rates in Japan have been very very near zero for nearly 20 years. I think they're borrowing money in Japan and lending it out in USA - what used to be known as the "carry trade".
If they're borrowing in Japan at 0.25%, and using that to run 0%, then it's costing them about $320 on a $50K machine, about $100 on a $15K machine (in total over 5 years). I think they're using Kubota's balance sheet to underwrite it - i.e. they're not looking at your credit rating, they're saying "we still own the tractor till it's paid off, Kubotas don't lose their value much, so there's no financial risk to the lender." So they don't need to charge you the 6% consumer finance rate, or whatever you'd actually be entitled to given your credit rating.
To me, that's also why they have the awesome KTAC insurance - they need to show their lender that no matter how stupid the buyer is, there's still enough tractor there to secure the loan. So they make you buy insurance that says "even if I'm a moron and wreck my tractor, it'll get replaced new for old."
Pretty much everyone says that there isn't much cash discount in it, and to me that'd be the reason. Of course, there are also differences regionally, I suspect based on the dealer. So some people get cash discounts, but I think that's more because their dealer knows they expect it than because the dealer has more bargaining room when you pay cash.
Note that my comments here are very specific to Kubota - so comparing to car sales isn't relevant if my theory is true.
