Are you asking for information or to chat with people about this topic? I would think a native speaker is better to learn from unless you are an absolute beginner with no knowledge of English at all. If you know zero English, I would get an English instructor who speaks your native language until you learn enough to form simple sentences perhaps.

I have an English teacher that is British. However, all my teaachers prior to highschool were not native English speakers. I also learned Japanese so far from non-natives. As you've said, in the country where I live (Israel) and many other countries where people I know live many people have difficulties learning English at a practical level, despite learning for six years in the education system. If I may share a story, my great-great-greandfather was an English teacher in Germany(born and raised in Germany). Later in his life, he moved with his family to the United States and sought a teaching job. Not only was he unable to be an English teacher nor a teacher for anything els, he wasn't able to work in construction building because no one could understand him. Of course, globalization and better schools helped this problem tremendously, but it remains a fact that non-native speakers hold much less efficiency in teaching, be it at fluency, slang, or accents (which are somewhat importent for being understandable and uproachable to natives). However, since they are not natives and learned the same way as you they may be able to teach you in a way more comfretable for you. Because they learned throuhg books they may know better grammer and more about different dialects. All in all, though, I think your'e right and it's a major obstacle.

My first Japanese teacher was native, but my second teacher is not. After graduating schools, I had a new teacher. With the first teacher, everything sounded natural, but the curriculum wasn’t too structured and the content didn’t have too many rules or formats to follow. With my current second teacher, there are some things that my first teacher says is unnatural-sounding, but the curriculum is very structured and the content includes sentence forms and formats. For me, it’s a difficult situation.