This is a very common statement but doesn't match my experience at all, unless you expand "business rules" to mean "not code already".

There's plenty of that work, and it goes by many names ("enterprise", others).

But lots and lots and lots of programmers are concerned with using computers for computations: making things with the new hardware that you couldnt with the old hardware being an example. Embedded, cryptography, graphics, simulation, ML, drones and compilers and all kinds of stuff are much more about resources than business logic.

You can define up business logic to cover anything I guess, but at some point its no longer what you meant by that.