$45 to graduate at Watkins Mill HS. Cheaper graduation ceremony?

How is it that graduation from Quince Orchard High School costs a mandatory $70, but over at Watkins Mill High School the graduation fee is only $45?  Both schools graduate from the same venue.  Note: this is what you see when fees are ILLEGAL!  There is no graduation fee set by the Board of Education, and so, principals can charge students whatever they feel like charging them!   

http://www.montgomeryschoolsmd.org/uploadedFiles/schools/watkinsmillhs/students/CapGownPayment%20Form.pdf