The writer makes a limiting assumption.
The benefit of price knowledge is not that you, alone and facing terrible consequences, will then be equipped to make rational choices. The benefit is that others before you will have done so. Their decisions and reactions will help prepare the ground for you before you ever step foot on it.
Technically, this means that current pricing in a functioning market tends to factor in past experience. Prices that once were too high tend to be lowered, and prices that once were too low tend to be raised, all without you.
Even if, in your own crisis moment, you can’t go shopping for health care, you get the benefit of the “shopping effect.”