Memory management, handwritten loops, pointers everywhere, absence of ready made data structures, error handling (or its absence,) epopeia with C strings, sanitizing inputs, and nausea from the slightest smell of SIMD, or basic binary hackery to begin with.
C was amazing when it was introduced, but is as archaic as COBOL today. We are stuck with it because of legacy.
Amazing was what Burroughs was doing in 1961, 10 years before C came to be, IBM RISC research in PL/S and PL.8, VAX/VMS stuff in BLISS, Solo OS in Concurrent Pascal, Xerox XDE in Mesa, ....
Those were amazing in the 60's and mid-70's.
It was not amazing. It was decent particular tool for particular job. That was all about it. Same thing about Rust. There are no silver bullets laying around.
It might be C++ instead of C for some of the above, but that doesn't make C "a legacy tool".
I’m saying it’s a legacy tool from the early 70’s that is absolutely terrible compared to what we could have.
Cool kids use it because there is no alternative.
Basic C can be picked up in very short time. there is nothing to be frightened about. When I first laid my hands on C I wrote working software (keyboard driver for DOS) in a first day as a learning exercise. Not sure what other than incompetence as a programmers is causing your expensive PhDs "fright of their lifetime".