Do you classify your Amazon FBA Selling Fees in COGS or Expense and why?

I briefly read the IRS pub and it simply states that COGS should be the landed cost of your product to an Amazon warehouse (which includes the freight from your manufacturer).

However, I see tools like A2X classify AMZ fees in COGS.

In my other businesses, I never classified merchant fees in COGS. Same goes for shipping the product to the customer.

Why do Amazon FBA sellers seem to do things against the published IRS guidelines/standard way of doing things?