The counterpoint to your argument would be that the hammer you buy at Harbor freight isn’t updated every month. If harbor freight came out every month and adjusted it to make it better then they would have to charge for that.
Fair enough. But I'm not demanding that they update the app free of charge forever. I have no problem with paid updates. All I demand is that I can use whatever I've bought for as long as I wish (or as long as it is technically possible to do so - e.g. until a major change happens in the operating system that breaks its functionality).
One of my favorite apps on macOS is Mailplane. They offer free minor updates, but you must pay if you want an upgrade to the next major release number. And I find that fair. I've always paid for every major upgrade, because I love that app.
When I said people that use it every day I meant for example like professional photographers that use Adobe pay a subscription. They don’t care because it’s just part of doing business and they pass the cost down to their customers.
That's also not right. Adobe was the first, or among the first, who took this shameless step of forcing customers to subscribe to their product. I will never accept that. Even if I were a professional photographer, I would buy and use something else just to spite them, because I despise their business model.
The fact that many professional photographers don't care, because they can afford to transfer the costs to their customers, doesn't make it right.
We have a clear example of this product/service dichotomy right in iOS, in the Music app. If we want unlimited access to unlimited music, then we have to subscribe to Apple Music. Maintaining the servers, paying the licence fees for all that music, syncing it with our phones, etc. are perpetual costs, which Apple must recoup. I'm fine with that. They're offering a service.
However, for the app itself we've only paid once (if we consider it included in the price of the phone). If we're happy to use the app locally, and to listen exclusively to locally stored MP3 files ripped from CDs, then we don't have to pay anything extra. Because the app itself is a product, not a service.