Real-world objects like these wear out. Code doesn't.

> Have you never seen a board with a revision number on it?

Of course I have. There's a difference though. You can't ship an electronic device that's unfinished with a promise to "fix it later". Yet this is what routinely happens with software these days. Also, if your device serves its purpose well, you'd probably have a "final" board revision with all flaws fixed. If you want to add features to an electronic device, you'd make it a different model, possibly sold concurrently with your existing one to serve people with different needs and budgets.

You just said "engineering". Bridges and roads are engineering as well buddy.

> Engineering projects usually have a finished state

This is the statement I'm addressing. And it's just not entirely accurate. Things change, assumptions get proven wrong, there's always a newer and better way to do something, etc.

Sure your widget was probably about as good as you could do at the time you first launched it, but several years later there's better components available. Or maybe a supplier stops making some part you were using. Or a few years later you start getting parts back failing early in their service life and need to make an update. What was once your finished state now isn't.