It does not get the job done fast and efficient, if you consider the develpment costs. The fast code the compiler generates could be genrated from other sources just as well, it's not especially the merit of that language.
It's written in C because the tooling to analyze and certify it for security in embedded/automotive/aerospace is targetting C (or C++). For some industries, Ada might be an alternative.
It may be paradoxical, but you're not going to be able to write safety critical software in Rust because the tooling to certify it for security doesn't exist and it'll still take years to get there.
Do I like this situation? No, I do not. Do I think it's a big problem? No, not big enough that it can't be solved by pouring money and engineering resources on it.
These certifications unfortunately often are on the level of the golden shields CAs provide to customers to put on their sites as sign of trustworthiness.
So yes, blessed is a nice word for it.
I see these "certified" stamps less as "secure" and more of a huge slowing down of progress and change - which strangely can translate to more secure since you know what you are dealing with.
If I can dream, I'd take a "certified" GNU Ada, or Rust, or something over C. But that is bound to take many years to happen if ever. I think we sooner will see Rust compiled to C which is fed to something like the abominable Greenhill so security consultants can pour over the intermediate C output and put it through the abominable Greenhill.
For example, generally, people use a lot of static arrays in C. Arrays are efficient. The way you program with fix-sized structures like arrays tends to be different to how you program with dynamically-sized structures and that style of programming tends to be more efficient.
In the vast majority of cases, a C or FORTRAN program will be more efficient than other languages not because they are C or FORTRAN, but because they force you to use an efficient paradigm.
Even other compiled languages like C++ or D are, more often than not, slower than the C counterpart UNLESS they are programmed in a "C style".
e: To be clear, the fact that they are compiled low-level languages obviously does help, but I'm trying to make the point that it's not the only reason.