That might be the chorus when it comes to selling new languages, but there is no reason C could not be compiled with memory safety. It is not done because by the end of the day people don't care for safety much.
Whereas, Ada, Wirth, and Eiffel languages were designed to make the job easier for users and tooling. SPARK was even tailored to make it easy to prove absence of C-style vulnerabilities with automated proving. That was done by a small team over a period of years whereas global assortment of teams putting decades into static analysis or proof tools for C haven't pulled that off outside even more restrictive tools like Astree Analyzer.
C is just inherently bad for safety despite safe ways of doing it existing. That's because it was designed almost exclusively to run fast on a PDP-11. That simple. On other end, Hansen wrote Edison for a ultra-minimal language for a PDP-11. It was smaller than C, easier to process, and still had safety features. Reiterates it was simply a personal preference by C's designers to not care about safety while many others did.