> Just take an immigrant in front of you next time and see him make two mistakes in a row in one sentence while casually talking to him (maybe he's tired, maybe he's lazy but who's to judge). You'd inherently think less of him, deep down, wouldn't you?

No, I wouldn't.

I think a lot comes down to differences in mentality:

- Many Germans think that they had a hard time getting to a decent level in English. So they expect the same willingness from foreigners to get to a decent level in German. (#)

- Many German native speaker really care about their language: It is a very common situation that German native speakers correct both native speakers and people who learn German as foreign language. With some people who learn German as second language, I get the reaction "Even if this is grammatically wrong, you nevertheless understood the sentence.". I do believe this person did not get my point: Among English native speakers I often observe this mentality for their native language, but I would really claim that "German language is a kind of thinking", so such mistakes really feel like a wrong-typed computer program.

So

> As an adult, I can never hope to compete on native German fluency with someone who's born and raised in Germany to educated German parents.

Being able to compete on this level is not something that is expected from you. But (also cf. (#)) willing to cram brutally hard to get near to this level over some time is.

---

Thus, to come back to your point:

> Just take an immigrant in front of you next time and see him make two mistakes in a row in one sentence while casually talking to him (maybe he's tired, maybe he's lazy but who's to judge). You'd inherently think less of him, deep down, wouldn't you?

As I wrote: I really wouldn't think less of this person because he makes mistakes. But - very in accordance of what I wrote - I would think less of such a person if he doesn't work really hard to get better in German fast.

In other words: It's really not about not making mistakes (everyone does), but about not working hard to get better.