Efficiency is a meaningless term when separated from ends.
For example, a motor that does nothing but cause vibrations is efficient for a hand-held massager, but very inefficient for a car. In the first case, the mechanism produces the desired end, and in the second it does not.
When someone calls cars "inefficient", and seeks government intervention for the sake of "efficiency", all they're doing is expressing a personal preference and trying to impose that preference by force on their fellow citizens.
I can go two directions here. The interstate system itself is a government intervention, where is your outrage about that? When talking simple scientific terms, efficiency is a function of energy put into a system and work returned from that system, nothing more. When it comes to cost effectiveness, it certainly costs a lot less to pay one guy to run a back hoe to dig a hole for a foundation than it would cost to hire 20 or 30 guys with shovels. When we are talking trains we are talking efficiency regarding the amount of freight tons miles/gallon of fuel and we are talking cost effectiveness when we consider the number of operators required. If it weren't for the interstate system, government intervention, you would see a huge difference in the placement of many businesses relative to the nearest railroad.