[ign0ramus]

I wouldn't say they are ignoring it. Case in the point that guide, you linked, recommends targeting recommends using C++17 which I think qualifies as modern. Compiler support for some of the newer features of C++2x hasn't matured yet.[0] That recommendation to avoid them seems sensible.

[0] https://en.cppreference.com/w/cpp/compiler_support#cpp20

[pjmlp]

Except ISO C++17 doesn't prevent random devs to call malloc()/free()/strcpy()/.... so modern is relative.

After reading those guidelines, I suggest reading Google's own code on the context of Android.