Corners of the new windows are very dirty or scratched

Judging by the pictures, the corners could also have been damaged during the installation of the windows, or during transport, or during glazing.

No, no and no.

What is installed is what was delivered - without checking if it was made without defects.

Everyday life on the construction site :) Welcome to reality...

Prominent examples are: BER, Elbphilharmonie etc.

There should be no foil,

There is nothing foiled either..that was just an interjection from Knallkörper about his windows.

Everyday life on the construction site

I still see a difference between manufacturers with their own installation crews and those with rental Santas from the student placement service.

The unfortunately only consists of faith and hope...

Should I tell the stories about how cars are built in Ingolstadt and Wolfsburg?

I believe none of you would buy a new car anymore if you found out what goes on behind the factory gates.

As I said... I don't see it that strictly... it looks like someone who fell asleep during the final inspection or set the tool incorrectly, or the service life has been reached, or or or... but all can be fixed with a few simple steps.

Even after the windows have already been installed.

Under no circumstances is a replacement necessary here. Except, as already mentioned, if the GÜ/window installer has money to give away.

No, no and no.

You can write "no" twelve more times if you like, but without arguments it won't help. You are an engineer too, so you should be able to argue ;)

At least we probably agree that there is a deficiency in the status quo. And I see it like 11ant, these windows should not necessarily have been installed like that.

I have described how this picture can come about and that it is not a big deal and that it can also be remedied in the installed condition.

I see no arguments from the proponents of replacement, except:

It looks crappy, (which is not an argument either)

that is no reason for removal and replacement.

Also, there is no defect here per se.

P.S. the three times NO were the answers to your three assumptions. But since it apparently was not understood, here again:

Judging by the pictures, the corners could also have been damaged during the installation of the windows,

No, then it would look different.

or during transport,

No, then it would look different.

or during glazing.

No, then it would look different.

Exciting topic. For me, mycraft's statement is plausible. And I also don't think that the GU replaces everything. I'm curious to see what happens.