> Given that Rust is quite an old language now and its adoption is still so low,

So being part of 3 major OS (Windows, Android and now Linux), the big 3 cloud providers having SDKs for the language, used by so much tooling (js + python) and being part of major internet infrastructure means its “slow” adoption then wow…

Very much so once you compare it to how quickly C++ (and, in fact, any language that's ever been in the top 5 or so) achieved similar milestones. Rust's adoption is very impressive when you compare it to, say, Haskell or Clojure, but not when you compare it to languages that achieved significant and long-lasting popularity. It's roughly similar to Ada's adoption when it was of a similar age (Ada was more prevalent then than Rust is now in some areas and less so in others). When work on Rust started twenty years ago, Java was younger than Rust is now. It was almost as close in time to the early work on C++ as we are now to the early work on Rust. Larger portions of operating systems were being written in C++ when it was younger than Rust is now.

There's no denying Rust's popularity in open-source CLI dev tools for Python and JS/TS, but when you talk to C/C++ shops who've evaluated Rust and see how many of them end up using it (and to what extent) you see it's not like it's been with languages that ended up achieving real popularity (which includes not only super-popular languages like C, C++, and Java, but also mid-popular languages like Go).