The federal power for eminent domain that allows for 'seize the land and deploy the bulldozers the next day, deal with the court stuff later' comes from the Taking Act[1].

States have their own eminent domain powers which vary, however in general they're easy to sandbag in the courts for years, preventing the state from doing anything while the landowners argue over the money.

[1] https://en.wikipedia.org/wiki/Federal_Declaration_of_Taking_...