It's been a long, long time since there was an abundance of completely free arable land that no-one had laid claim to. You aren't talking about "the old days",

It's been a long, long time since there was an abundance of completely free arable land that no-one had laid claim to. You aren't talking about "the old days", you're talking about the prehistoric days when there were few humans. Saying "farming isn't an option because you can't get land for free" is, IMO, a bit of silly argument. Arable land is (just like everything else) a scarce resource in a heavily populated world; it's not by someone's evil machinations that you can't freely have as much of it as you please. That's not slavery, that's competition for scarce resources. If you did want to farm, it's (very roughly) $1k/acre in many places, and you only need a couple acres to feed yourself.