Unfortunately, all C/C++ compilers have as the default option to omit bounds checking, but any decent compiler has options for enabling bounds checking and other run-time checks suitable for catching all the undesirable behaviors that are undefined in the C/C++ standards. The default should be to enable such options globally for any program and to disable them selectively only for the code parts where benchmarks have demonstrated that they prevent the program to reach the target performance and code analysis has concluded that the erroneous behavior cannot happen.

The claim that C/C++ are unsafe programming languages is only in small part true, because most of the unsafety is caused by the compiler options that are chosen to be default by tradition, and not intrinsically by the language. The C/C++ standards fail to define a safe behavior for many situations, but they also do not prevent a compiler to implement the safe behavior, e.g. the fact that the standard does not require mandatory bounds checking for accessing arrays and structures does not mean that a compiler should not implement such checking.

When a C/C++ program is compiled with safe compilation options, instead of the default options, then it becomes quite safe, as most errors that would be caught by a "safer" language would also be caught when running the C/C++ program.