builtin interpreters doesn't equal an os. Most of the time the os doesn't have a general purpose interpreter in the kernel even if they have an interpreter for

builtin interpreters doesn't equal an os. Most of the time the os doesn't have a general purpose interpreter in the kernel even if they have an interpreter for important os functionality(sh/bash/powershell). And even then most of the time these interpreters aren't meant to be embeded in applications. It's a fair point about postgresql but dbs that need max speed/control at times are an exception not the rule.