the point was that 99% rate of success is good enough when failure means nothing, not so much when it means dead people.

So, a treatment that cures cancer 99% of the time but kills the patient 1% of the time is unacceptable?

You have to look at the benefit of something when balancing against a cost.

Consider that the average person interacts with motor vehicles much more often than they would with a potential cure for cancer

And the same argument can apply there as well.