Well, there's huge differences in the scale of eminent domain projects. A new rail line is likely to affect a huge area with a whole lot of people, many of whom vote. You have to get politicians on board representing many different areas of the state. How do you convince the guy who represents a district that is just "passed through"? It's a pure negative for his constituents.

Not saying it can't be done, but it's a whole lot harder than building a shopping mall, that displaces a handful of houses.