As someone who used to be a part owner of a tackle business I feel somewhat qualified to ask/answer some of the questions that you pose in your excellent article.
There are some manufacturers who do indeed offer very good deals to the larger retailers, in either better discount or "free" additional rods/poles etc.
There are also some manufacturers who have a "not lower than" pricing policy that if you are found to have broken, then they will cease to supply you with goods.
None of this is exceptional but rather simple business practice and sound economic practice at that.
There are also some mail order type shops that will charge you the full RRP if you wish to spread the cost, by cheque or credit card, as opposed to a cash or one time credit card transaction. And quite rightly too, indeed Jeff, you answered this yourself, the shop has laid out the money for the goods and requires to make a reasonable profit on a sale over reasonable period of time.
Think about the costs associated with; purchase, transportation, insurances, storage, high interest on short-term loan and overheads? Not to even mention the ever-present problem of pilfering and shop lifting.
On the subject of personal service form your local tackle shop, I could not agree more. Sadly, we do face the problem of "use it, or lose it" in many cases.
In my opinion I prefer to walk into my local shop, spend time examining my proposed purchase, discuss the pros and cons of different options with an experienced angler/owner as opposed to mailing an order and waiting for the goods to arrive.
There is, however, more than enough market for both alternatives and long may it remain so.
Otherwise, we may well in the future be faced with the (unacceptable) position that the local shop will only be able to sell and compete on the smaller items, and bait, with the large mail order company's who will have the entire rod, reel and 'expensive' item market!