[the_why_of_y]

I see, you are merely unfamiliar with terminology.

The word "static" refers to compile-time; a static analysis reports errors or warnings based only on the source code of the program.

Sanitizers are dynamic analysis based on instrumentation. https://github.com/google/sanitizers/wiki/AddressSanitizer

  The tool consists of a compiler instrumentation module
  (currently, an LLVM pass) and a run-time library which
  replaces the malloc function.

In order to detect bugs with sanitizers, you have to find a test input that actually moves program execution towards UB. This is best done with a fuzzing setup like clusterfuzz, and lots and lots of CPUs, which Google fortunately has no shortage of.

https://github.com/google/clusterfuzz

As Dijkstra said, Program testing can be used to show the presence of bugs, but never to show their absence.