Everyone's spot on.
One thing I didn't see. Some dealers are part of a large corporation and they transfer equipment back & forth between their dealers. Sometimes one dealer has a tractor that's been sitting on their lot too long, and they'll transfer it to another dealer who might have someone interested, or the market locale is "better", or whatever. If it's been on another dealer's lot for a while, it could have been test run a bunch of times by customers, or it could have simply had the key left on at some point. Or it could be one that was run out to the front of their building and back every day for X amount of time, accumulating hours each time. Could be a million reasons. I personally don't like selling them if they have more than about 2 hours on them, or more specifically, I just feel bad about selling them with that many hours. Sometimes it's unavoidable but I personally disclose why the hours are there to the person buying it. Some aren't comfortable and that's understandable and respectable; I'll give the option to buy one out of a crate (which may put a delay in the sale process).
Sometimes there's buybacks too...maybe a customer bought a tractor, didn't like it, and Kubota bought it back & gave 'em another one. I've heard of this happening, and usually (from what I know), they are supposed to disclose the history, and give a pretty good discount.