.. which came from the philosophical and cultural ideal at the time which aimed for a simpler life.
European “simplicity” included colors from nature with natural dyes, natural fabrics (linen, wool, silk, some cotton), and “plainness”. French designers took these concepts, so French high fashion of the mid 1770’s seemed to have the same shape, colors, and fabrics as the Colonial’s, but the French added fancy work, ornaments, trims, and “flashy” details.
French “Colonial Fashion” was not much like Colonial fashion once they got done with it.
(Portraits: American, British, French high fashion. Same idea; different ornamentation)