> I get that you don't do any actual physical labor

Well, I personally do the physical labor (if you call riding around in an air conditioned tractor physical labor). You are right that the landowner doesn't.

> but don't you have to negotiate deals with labor suppliers (or laborers), seed/fertilizer suppliers, check on the quality of work and the condition of the land, facilities, and equipment?

That's on me, not the landowner. Why would the landowner do any of those things? Again, their only job is to count the money.

> then what's the ROI?

For me, mostly the fun. I enjoy it. I do also make pretty tidy financial profit doing it, which is admittedly a great bonus, but I expect I would still do it even if that weren't the case. Not everything in life has to be about money. Sometimes it's okay to bask in the pleasure of a hobby.

> It's hard to imagine that small-hold farming is as easy (and has similar returns) as buying an indexed fund

An index fund will, on average, provide greater returns than renting out your land, albeit with greater risk as greater returns expect. You wouldn't move to the country as some kind of get rich quick scheme.

But, if you've somehow already forgotten what we're talking about, when you are already living in the country for whatever reasons life has found you there, the land provides an income that offsets the cost of the necessary transportation.