Yes. It is an absolute miracle that 99% of the technologies and soft that we use today kind of work a bit. Nobody (including devs) usually sees or understand the big picture of these system, and when one attempts to understand it, he usually ends up facing such horrible things.

Yes. Devs program usually in high level code and dont understand bit level coding or basic electronics. Electrical enginers dont understand the chemistry that goes into building stuff and chemist dont get production lines. It is all messed up. But it works.

How many actually distinct impls of these things actually exist in the world?

Well, some of these units use superconducting chips (cryogenically cooled), so make with that what you will