I remember my Form 6 English teacher (a native English speaker of Irish descent) teaching us that students of the English language are expected to eventually have an intuitive sense of whether something you hear or say is correct or incorrect English. If you hear or speak bad English but don’t know that to be the case, your have failed to learn the language properly. End of story. You are not absolved of your language sins simply because you are not a native speaker.
Similarly, when I was in B1 French, one of my teachers talked about “internalizing” the grammar of French. If you have the grammar internalisé — that is, if you use grammar at a subconscious level, just like what native speakers do — , you are doing fine. If you fail to internalize the grammar, then something is wrong with the way you learn.
In short, the goal of every non-native speaker — from the perspective of language teachers — is to gain a native-equivalent intuition.
This stands in stark contrast with how “nativeness” is seen in the professional translation world. There, if you are a non-native speaker, you are often not expected to deliver native-level quality — in fact, many expect you to deliver outright substandard work.
This is a self-fulfilling prophecy: When you are expected to do poorly, you do poorly. I can speak from personal experience: Ever since I read about translators being supposed to only translate into their native language, my ability to use English has been steadily decreasing — to such a point and in such a marked way that it actually interferes with my ability to work as a volunteer translator.
When native speakers fail to use language correctly, we call it a speech pathology; when non-native speakers fail to do the same, some prefer to call it non-native speech. (Thank you very much. I prefer to call it — if we are talking about someone who has learned English for a long time or who is living in an English-speaking country — also a speech pathology.) Rather than being tolerant or sympathetic, what this really does is to create an expectation in the non-native’s mind that sets them up for failure. I can make no other conclusion than that the “native language requirement” is doing more harm than good.