Exactly. Why try to make something open source community stuff when we can just order cheap stuff from China. China is wonderful. China has solved the problem for us. We can rely on China.
Diesel engine design is non-trivial. It takes a lot of compression to get the heat necessary for ignition. It takes strong structures to handle that pressure. The fuel injector has to be able to overcome the pressure of compression and spray fuel into the cylinder. You need to get more energy out than you spend on compression and injection. The thermodynamics are complicated. That all gets built into the dimensions of the metal parts, and it all looks simple, but it's not. Those little engines doesn't even need a glow plug to get started. Or even much cranking. They just work. Cheaply.
For what it's worth, the AK-47 design is not "right", it's "good enough" and cheap. Some of the other militaries that copied the basic shape to share the ammunition significantly improved the design. For example, https://www.firearmsnews.com/editorial/best-ak47-rifle/39474...
It's rare to see common sense on Hacker News.
1.4 billion people who get things done verse fat nerds in basements talking stuff and can't even get their theory right. Open sourcing an X they have never actually used.
What is of interest is why China and not Africa or India or Brazil (BRICS+) so much, this is where the discussion is at.
Perhaps, could the fat nerds work with China and do things? This is controversial, NEETs can't even do advanced high school math anymore. They have given up.