ICAO Test for natives

From what I read, being native doesn't mean you speak fully smoothly and correctly for communication. There are better English speakers in Eastern Europe than in regions of Scotland, not when it comes to basic vocabulary, but when it comes to pronunciation. You may have an easier time understanding an East European or an Asian than someone with a thick Dublin accent on the radio, so no, they do not get a 6 automatically, as those can be two different things. But fairly enough most of them do get ICAO 6

Short answer: no, there is no automatic Level 6 for a native speaker, and yes, they still have to be assessed. ICAO's own personnel licensing FAQ carries this exact question, "Do native speakers need to be evaluated and how?", and the answer there is that they do. What changes for a native or expert speaker is the form of the assessment, not whether it happens. The practical route it describes is an interview with a representative of the licensing authority, a flight examiner for example, rather than the full test a non-native sits, with a referral to a specialist if a speech impediment or a very strong regional accent shows up. On an EASA licence the rule is FCL.055. Paragraph (a): a pilot who needs the radiotelephone may not exercise the privileges of the licence and ratings without a language proficiency endorsement on it. An assessment is what puts that endorsement there. Nationality does not, and FCL.055 contains no mother tongue or native speaker wording anywhere in it. Worth knowing for later, FCL.055(c) requires the endorsement to be re-evaluated every 4 years where the level demonstrated is operational level 4, and every 6 years where it is extended level 5, and it excepts pilots who have demonstrated expert level from that re-evaluation. Intervals quoted online for ICAO and for EASA are not always the same, so for an EASA licence work from the Part-FCL figures. On the accent point raised above, that is exactly why there is an assessment rather than a nationality shortcut. Pronunciation is one of six rated criteria, alongside structure, vocabulary, fluency, comprehension and interactions, and what it measures is how far your accent gets in the way of an international listener understanding you. Having an accent is not the thing being measured. Being hard to understand is. That cuts in both directions, which is the point you were making. Sources: ICAO's personnel licensing FAQ, and Part-FCL, FCL.055.