The PHP runtime does know the types of all values at all times, though, in a way that the C++ runtime, insofar as it can be said to have one, does not. To call that type _safety_ is a little much even by the standards of dynamic languages, because PHP is so willing to do implicit type coercion, but _at runtime_ a PHP program is certainly more able to detect type errors than a C++ program.

Comparing PHP with C++ is just silly in the first place. Nobody is trying to seriously write a deferred renderer that can do global illumination in PHP.