Labor Day honors the end of summer. American’s like holidays. We shouldn’t complain.
The decision to switch to a five day week was obviously a critical in the development of the frum community since under the previous standard six day week, it was almost impossible for a frum Jew to find work except in a frum owned business. Indeed, until the Civil Rights Act of 1964, even Friday afternoon were a problem during the winter months. However the switch to a shorter and more flexible work week has nothing to do with Labor Day.