So finally, who is to blame, when the window is not even? The builder? No! He did nothing. The windowing subcontractor?? Technical yes, but practical he just used hired workers. Some times ago, it was possible to say: Here we have a good company, with good reputation, the workers are proud to work for it ... Today, it is just a blaming game -- and when one of the subcontractors is sued because of bad work, they file bankruptcy, because there is also no financial basis -- the companies are just empty shells.
What also adds up to this is, that on every level of this game, only the price of the service is evaluated today -- not the quality. I also saw cases, where the builder company was a big one with great reputation, but the execution was awful! The reason: Bad contractors.
Another reason in my country is, that the requirements for workers in the building sector have been deliberately drastically lowered by the government, to make way for even cheaper work.
Today, (at least in my country) one that wants a house for his family to be build, has no means to decide, if the company will succeed and make a good house or will build a horror house. In most cases, there will be several topics where the execution was bad or really bad and you can call yourself lucky, when the additional costs after the house was finalized are moderate.
There are some really bad cases, where families thought the house would be ready in time and canceled their rent-flat just to be on the streets afterwards, because their house was not ready even months after the deadline. Some where never finished.