Not saying you're wrong, I'm just pointing out that private ownership of farmland was probably encouraged as a way to incentivize farmers - work the land yourself, do it for your self as number one beneficiary, you're more likely to work better, and not clock out (as much as possible for something like farming). Whereas people working state owned land might just say 'feck it, not my problem', picking the path of least resistance as it were. It's entirely possible that companies exploiting this came about as an unintended (initially) consequence.

There's also a situation currently where multiple small land owners rent out their land to be worked by a single well-equipped group of farmers and get paid on the yield minus whatever labour costs. This is in order to combat the inefficiency of working your own small plot of land with less powerful machinery or avoiding to invest too much in your own equipment (farm machinery is very expensive). Now the fairness of that trade-off is still questionable, but probably more than the current overall exploitation, if you have trustworthy folk.

Back to your point, human beings are incredibly selfish. You either do it for yourself and yours, or are taken advantage of by somebody doing just that. It's always the interest of everyone, it's just the definition of 'everyone' that differs

Ideally, I think public land should not be owned by anyone, not even the state. Land belongs to whomever makes use of it (and no, making use of it does not mean fencing it up and letting weeds grow because it's not profitable) and that may very well change from year to year.