I find this same scenario in all types of retail environments. For example, I know a fair bit about Martin guitars, having played them for over 40 years. I’ve made it my business to know the particulars of most of the models in their lineup, and can discuss them somewhat intelligently(usually). Yet it never fails that when I go into a major retailer to kick the tires, the sales force typically knows very little about them. Small shops are just the opposite, with the owner typically onsite and ready to answer any questions.
The best we can do is educate ourselves and be prepared to make smart buying decisions, with or without help from a salesperson.