Interesting question.
I'm reasonable certain that the concept of Spring Break originated as secular recognition of the religious holiday of Easter. And while this may not be politically correct to say, I suspect that it originated in the Northeast where the Catholic church had strong influence over secular activities. (When I was in school, we didn't have Spring Break. That was a long time ago, but I also grew up in the South where the Catholic church was decidedly less influential.)
Today, it is my sense that Spring Break is viewed mainly as an entitlement to both teachers and students, and it is no longer a secular adjunct to a religious holiday.
A related question might be asked about winter break. Winter break originated in the early 1970's during the 'energy crisis'. It was intended as a means by which schools could reduce their operating expenses by turning down the heating during the heart of winter.