That has nothing to do with high level, C++ for example also had no built-in guarantees for a long time. Making no promises about timing simply means that threa

That has nothing to do with high level, C++ for example also had no built-in guarantees for a long time. Making no promises about timing simply means that threading is either a non concept in the language (see C++ before 11) or the language declares everything to do with threading unspecified or undefined.