Although we didn't tour Tepic (or Nayarit, for that matter) as extensively as did you, from what I saw I would agree. With one exception - close to the zocalo is a modern department store. We went inside, and my wife commented that with the exception of the language on the signs, she could easily have been in the Macy's store at Bellevue Square, the most upscale large shopping mall in the Seattle area. They had almost identical merchandise displayed and arranged in almost exactly the same ways. Shoes, accessories, cosmetics, clothing, home furnishings, ...
Overall the store was probably about one-half the size of the Macy's here - more similar to the square footage that I've typically seen occupied by a J.C. Penney store in big city suburban US shopping mall. Translating pesos to dollars, the prices were only about 20% less than in our neck of the woods here in Seattle. And the place had lots shoppers that Saturday morning in April, the Saturday after Easter.
Other than language, the only thing different from the US was the presence of an armed guard at each entrance to the store. The guards were also quite alert and attentive all times we noticed, and looked closely at each person entering the store. During the ten or fifteen minutes we were inside the store I did see a guard intercept a couple of people who were entering the store and refuse them admittance.