Anyone who feels this plays into the sale of basses in any way (or musical instruments) is a fool, period.
The list prices don't come from the individual stores. If shipping is being calculated into the price, its being done by the manufacturer. Not the retailer. It become the price of the instrument. Its like playing a game of semantics. Companies cut corners one way, and tack $$$ on another. Today you can get a bass of WAY better quality than you could in 1970, delivered for FREE to your door, for less than you would have had to pay in 1970 WITHOUT shipping. So shipping being a part of the price doesn't amount to a whole lot. That money is most likely being skimmed off some other place. I'm not even so sure manufacturers are actually even doing that. Just wrote all that for the sake of argument.
Also, if 5 online stores are advertising "free shipping," but Joe Schmoe Music on Main St. can't afford to do that, guess what? Then those other places are offering free shipping.
I'll add to that the fact that there are MANY items Amazon sells cheaper than in stores, and offers free shipping AND returns. I bought 2 winter jackets in Macy's last year because they were having their huge blowout sale. Signs all over the store saying 50 to 70% off. I got 2 Tommy Hilfiger winter coats for under $100. I was thrilled, but felt duped and typed the item numbers into Amazon when I got home. The jackets were $10 less on Amazon, no sale, no nothing. No shipping either. On principle, I returned the Macy's jackets. Had they not duped me with the 70% BS I would have kept them. Yeah, it was childish on my part, but I hate deceptive advertising.