How would the govt. make infrastructure improvements like high speed trains if it couldn't use eminent domain, though? It's an intractable problem to negotiate with everyone along a path simultaneously, and if they hit a block of people unwilling to sell, and the train couldn't be made to turn fast enough to avoid it at speed, you'd either have a very slow train, or they'd have to waste another x months negotiating a different path. We trade absolute liberty for pragmatism.