You might be confusing a few things - older steering columns were very rigid (and thus "strong"), but were also a fairly major concern in frontal or rear collisions: they would essentially impale the driver if hit at the right angle.

Modern steering columns have a telescoping construction that allows them to collapse in the event of an impact so that this isn't a big of a concern.

It doesn't matter whether it is a servo or a human that turns the shaft, the design loads are a function of the weight of the car and the front/rear weight distribution as well as of whether or not the front wheels are driven or idlers.