Why does government employ the power of eminent domain?
2 answers
It's in the public interest to have some land set aside for the public, not private, use.
Eminent domain is used when a private owner of property refuses to sell to government for public use of the land. For example, if a new road needs to be built, or an existing road widened and one or more landowners refuses to sell or ant too much money, the government may use eminent domain to take the land, with fair compensation to the private owner.