What is more expensive? Masonry or windows?

It’s not clear to me either, the salesperson didn’t reveal any information and also didn’t negotiate. It’s of course clever, that way you avoid negotiations before the contract is signed.

Masonry costs almost nothing. Windows, on the other hand, are damn expensive. Makes sense, right?

Windows have glass components, need to be manufactured elaborately, and then installed. Also, several people earn good margins on windows.

You can easily lay those few bricks yourself if necessary, and then it won't cost you anything at all!

Windows are more expensive. I assume that a general contractor (GU) who does not pass on the additional costs is making up for the money elsewhere.

Depending on the size of the windows, the structural engineering is also more complex. Windows are not even included in trades like exterior plastering because although material is saved, the work becomes more labor-intensive.

Shading (e.g. roller shutters) is also relatively expensive.

In addition, there are also windowsills (inside and outside), where material + labor have to be paid.

We were actually able to install our masses of windows wherever we wanted, including asymmetrical ones under the roof or window bands. No extra charge.

"Giving" the price difference to the builder is cheaper than fifty-seven changes just for the pathetic attempt to fit the house millimeter-precisely into the budget.

Likewise, several people earn good margins on windows.

Nothing is earned on plastic; the money just changes hands – at least with single-family houses. You can barely keep your people afloat with it anymore, thanks to "price-conscious" customers. Nowadays, builders try to recoup from the windows what the barrier-free shower, the venetian blinds, and the electric double gate of the king-size junk garage cost.

Masonry costs almost nothing. Windows, on the other hand, are damn expensive. That makes sense, right?

Windows have glass components, need to be manufactured with a lot of effort, and then installed. Also, several people make good margins on windows.

You can easily lay those few stones yourself if necessary, and then it won’t cost you anything at all!

Are you serious? I’m building my house myself with a master mason friend.
Masonry is often underestimated, it feels like. It’s not just about laying bricks, what about the whole concrete topic (reinforcement, formwork, possibly precast ceilings, …), measuring, … in the end everything has to be right, not only the heights but also the statics. That’s actually not trivial at all, and as a layman you can only interpret a statics report…
Anyone thinking about building with a general contractor (GU) often isn’t close enough to building to master all that on the spot. After all, a masonry apprenticeship takes a while and you don’t just get a master’s certificate for free.
Once everything is right — height, corners, and you just have a masonry wall — it really goes quite fast… But you should definitely have an expert at your side for that. Then the house will work out, but as a complete layman I would definitely advise against doing it alone.

The builders are trying today with the windows to recoup what the barrier-free shower, the venetian blinds and the electric double gate of the king-size junk garage cost.

That surprises me and I cannot understand it. In my assessment, few things are as important as windows. I could certainly do without the things you mentioned and wouldn’t even miss them. Let’s see how many windows our house will ultimately have. Oh, if only I could have things my way.