[tadfisher]

This is correct. In cars with hydraulic-assisted steering, you're forcing fluid back through the pump, which is quite hard to do in addition to the fighting the bulk of your car and steering rack. In cars with electric-assisted steering, like the Prius, you're working against the electric motor using a belt and pulleys.

Which begs the question: why isn't the electric-assist motor designed to freewheel when power is lost? Losing steering assist at speed would be a more manageable situation.