I'm going to politely suggest that you're way off base, and considering that I run one of Canada's most successful on-line businesses I know of what I speak. We ship acoustic guitars all over North America. At approx $45 per carton delivery cost is a major consideration, both for us and for our customers.  

Throughout the year we focus on reducing those costs...tighter negotiation with carriers, more efficient packaging, and any number of other small details that bring the price down. I think its safe to say most on-line retailers do the same thing and are quick to pass those savings on to customers. When we reduce ancillary  costs without sacrificing product quality the consumer reaps the benefits.

When we offer free shipping, as we are currently doing, the cost of the freight comes right out of our per-guitar bottom line. For customers it is a direct saving. For us it's a chance to evaluate whether the additional volume makes up for the margin hit. 

That's free for our customers!