Quote from dsandys
Horses eat, minecarts are powered by gravity, redstone or coal. So whence comes the power for a long boat trip? The boat itself isn't powered - it comes from the player. But if the game developers have designed that power to come without an energy cost to the player then so be it.
thats a weird argument. If you flip a lever it produces power forever, where does this energy come from? In most videogames it doesn't work like that. And you might report the bug at the Minecraft bug tracker