It matters for real-world software development, though the reason may not be intuitive. In theory, for any particular bit of software, you can write code in any

It matters for real-world software development, though the reason may not be intuitive. In theory, for any particular bit of software, you can write code in any of these three languages that has nearly identical performance. In practice, the complexity of expressing equivalent performance can vary considerably depending on what you are trying to do. There are finite limits to the complexity cost developers are willing to pay for performance. Because the cost in each of these three languages is different to express some thing, sometimes there will be a threshold where in one or more of these languages most developers will choose a less optimal design. This manifests as practical performance differences in real software even though in theory they are equally expressive with enough effort. This comes with another tradeoff. Efficient expressiveness relative to software performance comes at a cost of language complexity. C is a simple language that has enough efficient expressiveness for simple software architectures. C++ is at the extreme opposite; you can do mind-boggling magic with its metaprogramming facilities that can express almost anything optimally but god help you if you are trying to learn how to do this yourself. Rust sits in the middle; much more capable than C, not as expressive as C++. This suggests the appropriate language is partly a function of the investment a developer is willing to make in learning a language and what they need to do with it. Today, I use modern C++ even though it is a very (unnecessarily) complex language and write very complex software. Once you pay the steep price of learning C++ well, you acutely feel the limitations of what other languages can't express easily when it comes to high performance software design. I used to write a lot of C. It still has critical niches but not for high-performance code in 2021, giving up far too much expressiveness. C++17/20 is incredibly powerful but few developers really learn how to wield that power, though usage of it has been growing rapidly in industry as scale and efficiency have become more important. Rust is in many ways an heir apparent to C and/or Java, for different reasons. Or at least, that is how I loosely categorize them in my head, having a moderate amount of contact with all three. They all have use cases where you probably wouldn't want to use the others.