That is not peculiar to software development, even the most sophisticated F1 motor or Raptor engine is composed of five or six "simple machines" based on only three principals: wheel (wheel, pulley), lever (lever, screw), inclined plane (inclined plane, wedge).
There is complexity in all areas of engineering of course. What makes software special is that it is so easy to create new software, and thus create more complex things.
In fact it is more difficult to create software with simple design than it is to create complicated software. A "hacked" thing becomes very complicated as it evolves. Software is isomorphic to logical proofs, we can think of how it is often possible to simplify mathematical proofs. It is a lot of work however to come up with simple elegant proofs. So it is with programs.
Mechanical devices have to be carefully designed because idea is that once you have the design you will then manufacture many machines having the same design. You need to do that because manufacturing physical devices is expensive. In software you can just start typing.
> How would you break down a coaxial swirl injector (an important part of the Raptor engine) into “simple machines”?
I didn't complete the Mechanical Engineering degree two decades ago, so you might want to consult an engineer. Preferably one at SpaceX )) Being familiar with only typical automotive electromechanical fuel injectors, which presumably operate on similar principals, I'd also like to see where the spring and solenoid are classified. The valve itself is obviously an inclined plane.
> Are the regenerative coolant pipes built into the Raptor’s nozzle a wheel, a lever, or an inclined plane?
I'm not familiar with the Raptor, but from examining an RS-25 up close a few years back I would say that the intricate regenerative coolant pipes that make up the nozzle are not mechanical devices )). They are a component of a mechanical device, though, in the sense that they are bolted to the same device as the e.g. obviously mechanical turbopump is bolted to.
Surely there's a certified engineer in the HN audience who could chime in.
> you might want to consult an engineer. Preferably one at SpaceX
I suspect that they would tell us that the idea that every machine can be broken down into a series of simple machines was a cute theory in the Renaissance, but is not a usefull model to explain how a Raptor engine works. Maybe the theory of simple machines and compound machines is usefull for purely mechanical constructions, like a bicycle or a clock, but fails to account for the fluid mechanical effects which dominate in a rocket engine.
