First of all, we did not build with a general contractor. It was already planned to give the house some color, so we had the free choice to select from the color fan. The desired color was then applied ready-mixed in the plaster and that was it. In our case, it was as follows: the applicator went to the building materials dealer and said "plaster mixed in color XYZ", please for quantity xxm2 and done. So either his margin was already so high that the extra "mixing" was negligible, or it is negligible because it "hardly" costs extra. And as already mentioned, this saves 2 work steps —> at least 2x painting of white plaster.