Totally different design. Rack and pinion vs steering box. Nothing to do with what is driving it. In both cases it is a hyrdraulic pump. In the case of the 80, it is better since it is gear driven and the belt can not slip or ever break, like it can with a 100.
Think of it as torque. The 80's steering is V6 powered. The 100's is V8 powered. The V8 power puts more stress on those components though the performance (turning factor) is much higher. How they don't break!?
The motor has nothing to do with it. Could be a v16 turning the pump.
If the 100 is superior then why are you blowing out steering racks?
PS. you will not argue that is the price to pay and preventative. That is BS. You should have regeared and not bought new driveshafts