At any one time, there are probably thousands of .com domains available to register that match an existing business. If they don't have an existing website then often their business doesn't justify one. These small businesses are generally direct customer facing enterprises. The repetitive cost of the domain, updates, and hosting just aren't justified. Why set-up a 24 hour sales channel and all that involves when your content with existing sales. Most would probably be satisfied with just an ebay outlet if they wanted to go online.