That's how it looks on the surface, but once you scrape off the dust, a different picture emerges. That's just over one dealer per state, not very many outlets at all. Many more exist, but they sell only a small percentage of the equipment. The customer base is very small and geographically spread out. Only in a few major population centers are there enough customers to support a specialized audio dealer.
Much equipment is sold via mail order.
My customers are my agents and report back to me what dealers tell them. They inform me that the dealers say they don't want to carry my products because they are not heavily advertised. So the few dozen primary outlets of distribution only want to carry products that are heavily advertised. Let's look at the economic dynamics of that statement. Most small companies don't have that kind of money for advertising.