I have talked to colleagues who wrote software running on microcontrollers a decade ago, that software still runs fine. So yes there is set and forget software. And it is all around us, mostly in microcontrollers. But microcontrollers far outnumber classical computers (trivially: each classical computer or phone contain many microcontrollers such as SSD controllers, power management, wifi, ethernet, cellular,... And then you can add appliances, cars etc to that).

If something in software works and isn't internet connected it really is set and forget. And far too many things are being connected needlessly these days. I don't need or want an online washing machine or car.

Ignoring the actual useful reasons to connect something to be internet, the subscription business model is just too damn tempting.