Isn't it not even a puzzle anymore when you have enough people around to keep the goats and wolves in check on both sides of the river and in the boat?
therefore human-sized hampster balls are an inefficientmeands of transportation? what are we going to do about people who want to do that in an environmentally friendly society? maybe just apply a tax on the inefficient methods and let people do whatever they want including walking, riding a bike, and taking transit?