[untamedmedley]

I agree that if your site metrics show large numbers of people set to buy but abandoning their purchase because the checkout process is confusing, then you should work to make it more user friendly.

But what I'm saying is every designer should be asking 1. How many people are having this unique difficulty and 2. Is it worth the time and COST to fix it? Moreover, will adding the information/steps to needed to clarify the process bore/put off the majority of customers who already know how to use this (for example, a tutorial that either adds an additional step or doesn't allow users to bypass it)?

A good designer should be able to plan for contingencies, but a good businessperson should be able to draw the line between pleasing a customer and watching their bottom line.