It continues: (from Adorned with Dignity)
Opposition to the Sheitel
At that time, when women from other countries began to wear sheitels, rabbanim opposed this practice and stated that it was a deviation from mesorah:
The Maharatz Chiyus declared, “It was accepted throughout the generations that all women were careful not to wear a wig in public. Even in my youth, I never heard of a woman living in our country who wore a sheitel; it just became a new breakage of the boundaries of mesorah.”
The Reform Movement
When the influence of the reform movement seeped into Germany and the surrounding countries, many women unfortunately began to uncover their hair. Thus, rabbanim ruled that women may wear wigs (as opposed to revealing their own hair). Additionally, in the early 1900’s in America most Jewish women did not cover their hair. This may be the reason why Rabbanim in America allowed the wearing of wigs.
The Era after the Holocaust
In the aftermath of the Holocaust, the generation was shattered physically, emotionally, and spiritually. (The Satmar Rebbe zt”l said that any person who survived the war and remained frum was on the level of a tzaddik and could evoke yeshuos for others.) Thus, due to the weakness of the girls, many were not ready to cover their hair at all after they got married. For this reason, even great rabbanim who were against the wearing of wigs allowed them to wear sheitels in order to save them from exposing their actual hair in public.