First, there are samples, and second, you can actually make the effort to go out of the house and look at other houses. You'll be surprised, especially in new development areas, that there is not only anthracite to see live ;)
So you immediately assume that we didn't make the effort? Bold claim...
I estimate we looked at about 300-500 new houses. Over 95% of German new-build houses have white or anthracite windows. The rest were Golden Oak, a few times green...
In Poland it is a bit different. There, well over 50% of the windows are either Golden Oak or Winchester-colored. We didn't even see any "experimental" colors in our area (Berlin-Brandenburg).
And yes, there is always a small sample about 15x10 cm in size. But that doesn't tell us how it actually looks when all the windows are covered with it. Windows in many colors are rarely found at the window manufacturers, as these are only made on request, since they are special colors.
This ultimately means either you dare the experiment that you won't like in the end, or you play it safe with the "boring" combinations.