In practical terms, yes. Adjusted for inflation, a modern iPhone costs roughly the same as the ones in prior generations, except now you get a lot more bang for your buck with better battery life, improved camera, etc.
iPhones aren't a monopoly (yet): they have to compete with Android phones still, plus Apple probably prioritizes increasing their marketshare and retaining customers over maximizing profit from iPhone sales. iPhones generate a lot of other profits from things like the app store, not just from the phone sales, so pricing the phones maximally would hurt those.