You are purposefully obtuse and I'm not sure what joy you derive from it but just to take your silly strawmen:
Laptops for the most part are put together from standardized parts and you can exchange the major ones (CPU, RAM, storage and often even the displays) from one brand to another and it will work. And if you go to desktop computers the range of parts that can be swapped out between manufacturers increases even further (power supplies, graphics cards, etc).
The 'highly optimized MacBook Pro' is as closed as apple can make it because they are trying to emulate car manufacturers, including 'model years'.
As for OS types, we have a basic common denominator, the boot environment and some abstractions which allow us to run a wide variety of operating systems on the same hardware.
And on that hardware you can run applications, which either talk to the OS directly using a standardized interface and there usually are a number of emulation options and VMs that allow you to run other operating systems and/or their applications, usually with some penalty but for the most part it works.
CNC machines use a lot of standardized tooling (I had a machine shop at some point, founded a CNC machine company, and I think I'm still in touch enough with this domain to be able to do it again if I want to today). Sure, you can't pull a board from one machine and stick it in another, but the G-code they use is for the most part backwards compatible to 1966 or so and it isn't rare at all to see a machine upgraded to the latest controllers and motors but keeping the frame, tooling and such.
Cars are over optimized to the point that the cost to society (in terms of landfill and recycling) is immense, there is most likely a point where a better balance between up front profits and cost to society can be found.