Go back and read the original post again if you must.
Its about value received for the price paid.
Here are some things the LDS could do that would make that equation work:
1. During the warranty for "X" (e.g. the transmitter in question) we will instantly swap a failed unit for a replacement, and we will keep one in stock just in case such happens (no return to manufacturer necessary)
2. Here, have an air (nitrox) card to go with that transmitter (thereby adding value, but adding far less cost to them than the "face value" of the card)
3. "Your first two overhauls on that regulator are free - yeah, the manufacturer throws in the parts, but we'll eat the labor. And your overhauls will be put in front of our service queue."
I can come up with a bunch more, but those just popped into my head immediately as things the shop could do to tilt the value scales in their favor.
(2) is particularly difficult for the mail order folks to emulate

(1) and (3) can be emulated (overnight shipping makes it possible for (1) anyway), but its nowhere near as effective.
Its overly simplistic to say that its just a matter of "price". The truth is that its never just about price. Its about value received for the price paid, and if the customer receives only the original product, and no additional value, then why are they paying the premium price? Just to be "nice" to the retailer? Why would you do that?