Its an interesting discussion in the sense that the general public still perceives what most sign shops sell as a product not a service (design). And most do sell a product, not a service, so the public is usually right in their assumption. The challenge lies in not marketing yourself as a purveyor of commodities but rather solutions for their business. At which point, stickers, wraps, banners are merely mediums to advertise their business.
Most shops fail to get past the idea of marketing a solution to the clients, hence why in most instances, design is undervalued, or considered 'included' as part of the product they are buying.
Of course, conversely some in the public do just need a product, and I'm sure many a shop makes a nice living selling them sign products, or vinyl by the pound.