This very issue has given me fits for as long as I have been into TTRPGs.
Do you know how many mundane skills an 'adventurer' would need at their most basic? Able to walk very long distances without rest. Able to scrabble under, over, and through shit in a pinch. Always aware of their surroundings (great at preventing instant death). Then there's the host of skills needed for camping and wilderness survival. You're going to hit a river or body of water at some point, and your boy doesn't have the most basic swimming lessons? We haven't even gotten to things useful for surviving combat yet, and we're already way past what most games even give you to invest in a character. Even if we offload as much as we can on to a hired NPC wilderness guide (adult daycare style with sherpas who haul rich people up mountains and their corpses back down), that still puts the typical starter PC way over budget.
And most systems are pretty tight assed about attribute allocation that 'basic fitness' is one of the first things to go in optimizing a build (as not optimizing puts you below threshold for default encounters).
What do you even do about th- Hahaha just kidding. I can't remember the last time a DM put such challenges in front of players. Probably because no one ever has them.