Earrings for girls

Q: Is it permissible for a girl to have her ears pierced? What is the difference today between earrings in one's ear and earrings in other places on the body?
A: The Maharik (#88) says that the prohibition against following non-Jewish practices including acts that are arrogant and haughty. An earring in a usual place like an ear is permissible, an earring in an unusual place which draws attention of others is forbidden. It is related in the book "Ve-Alehu Lo Yibol" (vol. 2, p. 172) that the daughter of Ha-Rav Aharon Lichtenstein (Rosh Yeshiva of Har Etzion) wanted to get her ear pierced but her father was uncomfortable with the idea. They agreed that they would go and ask Ha-Rav Shlomo Zalman Auerbach and follow his ruling. When they asked him, Ha-Rav Auerbach Shlomo Zalman said, "What is your question? By us, we give the boys a Brit Milah and pierce the girls' ears."
Q: Why is piercing an ear a "usual place"? Perhaps it was not always the usual place and now it is? Perhaps an earring in another place became the usual place?
A: We follow the reality, what religious people do at a particular time, and one who deviates from that is transgressing.