If you own land, you would owe land value tax, regardless of what you have done to the land. If you just hold the land and do nothing you still owe tax. No one forces you to sell the land.
This:
>When there's a more profitable use for your land than you are current exploiting, you must give the land up
is not accurate.
> Land should be collectively owned by the people living on it and producing from it.
From wikipedia on eminent domain: "The property may be taken either for government use or by delegation to third parties, who will devote it to public or civic use or, in some cases, to economic development." The government, using eminent domain, literally forces you to sell the land. That is what the law is.
What part of that isn't true? They can take private land for public or "economic" development.
> Why should this be the case?
Private property is theft. Private property is a tool used to expropriate value from producers (workers) and give it to the property owners (capitalists). If you have a mine, a person or a corporation owned by a small group of people, buys the deed for the mine. They pay workers to extract the resources from the land for a wage. The wage is necessarily less than the value the workers create by mining the resources. That surplus goes into the pockets of the capitalist owners, even though they did no work. The miners are likely paid pennies, live in poor conditions, and now their home land is ruined by the ecological effects of the mining operation.
Resource extraction happens to be the easy one to describe, but the exact same principle holds in all manifestations of private property.
If you disagree, please at least read some Karl Marx first. Criticism of capitalism is well examined, and has been done for a long time.
This:
>When there's a more profitable use for your land than you are current exploiting, you must give the land up
is not accurate.
> Land should be collectively owned by the people living on it and producing from it.
Why should this be the case?