a) Undeveloped land is freely available, and anyone who wants to can go and cultivate it independently from anyone else, making a life entirely for themselves.
b) All land is already owned, and making a living must be achieved by exchanging (typically labour) with others.
Do you believe that people starting without capital in scenario b) will enter into contracts as freely as those starting without capital in scenario a)?
a) 100% of the world population can relocate globally without any need for visa so they can access the global job market and pick the best location
b) 1% of the world population has access to enough education to become highly skilled and be able to relocate legally. Everybody else has limited choice.
Another example:
a) Everybody has access to UBI and can freely choose to work or study or do volunteering, art etc
b) Unemployed people go hungry, homeless, get sick, get imprisoned