Well, I wouldn't mind buying the street that my house sits on just so that I can use it to block traffic and give everyone a hard time. People can always take another street, even if it adds an additional ten minutes onto their travel time. I mean, it's just like a board game! Annoying people is fun!!!
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I hate to take the point counter to the extreme free market position, but Everett has a point. If there's a highway and an owner buys it from the goverment and doesn't want anyone on it, he could keep the road all to himself. This would prevent many people from getting where they want, and cause an inconvinience in trying to find another route. However You could have public roads and have the private sector charge money to maintain them. Although I hate being moderate, I think this stance might work alright.