Outdoor water tap was not connected!!!

Who was in charge of site management? What does this person say?

I assume "GC instead of detailed planning" ...

That's why I was surprised that the plasterer didn't notice anything...

That he didn't say anything doesn't necessarily mean he didn't notice. He simply doesn't care because it's not his problem. It's the classic case where everyone only does what's in their contract. If the plasterer had said "hey, there's a pipe missing," it might have meant a pause for him. The client first has to run around and find who's to blame, that person has to fix it, and then it continues. It's quite understandable that the plasterer doesn't want to fall behind schedule because of other people's mistakes.

Plastering crews usually get paid by ProHaus. The faster they finish, the better the earnings. The missing pipe just delays things. Quickly plaster over it and move on.

What you are all discussing here, whether someone saw it or not... whether they didn’t want to see it, truly didn’t see it, or deliberately kept it quiet - the fact is: we don’t know and it doesn’t change the result :)