It turns out the answer to this question lies in the sumptuary laws of sixteenth-century Switzerland. The nobility at the time made laws that determined what each class could and could not wear.

The laws often prevented commoners from imitating the appearance of aristocrats and could be used to stigmatize disfavoured groups. In cities of the Late Middle Ages, sumptuary laws were instituted as a way for the nobility to limit the conspicuous consumption of the prosperous bourgeoisie. Such laws continued to be used for these purposes well into the 17th century.

Because the majority of Anabaptists at the time belonged to the peasant class, they were allowed to wear only the plainest of clothing. This fit well with their belief in modesty, so they became some of most willing adherents to these laws. Long after the sumptuary laws no longer exist, the Amish and Old Order Mennonite descendants of the European Anabaptists, continue to wear plain clothing.

This is another example of how bound the Amish are to the traditions that have carried down through the generations since the Anabaptist movement began in 1525.