Not disputing your point, but providing information: (...) It's called the Freedom to Roam.
More like disinformation, almost all significant rights to live off the land belong to the land owner. Here in Norway the freedom to roam gives you the right to do what would normally be considered trespassing in the US, but you can't make any long term campsite, cut down any trees, do any hunting and hardly any fishing in lakes and rivers without paying fees. You can fish on the coast and collect wild berries and mushrooms, herbs and flowers with relatively few restrictions but they're made to discourage any significant commercial use and would also practically make it almost impossible to live off.
It's primary function is that you can roam in nature - walking, biking, swimming, kayaking, canoeing, cross-country skiing and so on. A secondary function is that you can stay a while for say sunbathing or camping out in a tent, you can also collect dead branches and such for firewood but not leave much of a permanent mark. Being able to collect some of nature's produce is a tertiary function and usually only those resources that'd otherwise go to waste, if it's a commercially viable resource there's usually restrictions like salmon fishing or moose hunting. Living off the land pre-agriculture was very tough to begin with, within the modern confines it'd be even harder.
And you'd probably starve anyway, because most people today aren't very familiar with the old ways of preserving foods like drying, curing, smoking etc. which are absolutely essential to survive the ups and down of a hunter-gatherer society. And just the fact that you were a tribe averaging your luck out across many individuals, hopefully at least somebody caught or found something. Agriculture and domestication brought a relative stability to food supply while the natural supply is extremely seasonal.