A big fraction of product cost is the overhead of setting up the manufacturing pipeline, so often the product tiers will be very small or even software changes to the exact same object.
This doesn't strike me as unfair. It's helped me recently, when I bought the lowest tier iPad pro (I don't care about storage or built-in cellular, and I want the smallest one). If someone wants to pay more for those things, let them. If it came full-price with all those features bundled, I simply wouldn't have bought it at all.