Sort of, but it is not a 1:1 relationship. The cost to ship a single item (online purchase) vs. the cost to ship a pallet of materials amortized over multiple items (brick and mortar).

Of course. But then there are all of the other costs that come along with a physical store location (property costs, utilities, staffing, etc. etc.).

Many of which an internet only retailer also has, but usually MUCH lower as they do not need retail locations in prime areas, which usually also results in lower utilities, etc.

And this isn't meant as a disagreement, just as a discussion of minutiae.

Not just MUCH lower, but MUCH MUCH lower.

Basically, an online retailer has a warehouse (and all the costs associated with the physicality of that) + a warehouse staff + a staff to handle shipping + cost of shipping individual items.

A retail company (and in this thread the focus has been on the big guys, Target et. al) has a warehouse (and all the costs associated with the physicality of that) + retail stores (and all the costs associated with the physicality of that) + a warehouse staff + a (admittedly smaller) staff to handle shipping + cost of of moving stuff from warehouse to retail store + retail store staff. So all the stuff an online retailer has to pay for (minus a small fudge factor due to increased efficiency of not shipping to individual addresses) and THEN all the stuff that comes with brick and mortar.