Maybe a single developer personally can write C/C++ code that is probably pretty safe (keeping in mind that most personal/small projects never get a proper secu

Maybe a single developer personally can write C/C++ code that is probably pretty safe (keeping in mind that most personal/small projects never get a proper security analysis/penetration test, so one may have a biased perception), but as soon as you have several people with non-trivial components that interact, it is quite to introduce serious problems accidentally. The evidence is unfortunately against C/C++: even the biggest tech companies in the world developing applications for which security is a critical feature (operating systems, web browsers) still regularly have bugs caused by memory safety issues, and they're almost certainly throwing every tool and a lot of CPU time at the problem.