All I can say is----the years that I worked at SFSL. I worked in the admissions dept. (You would think that the admissions dept would know the attendance at any given time). Well This dept at SFSL relates to ticket sales, ticket takers, GR, and season pass processing. At SFSL the admissions supervisors came around to every turnstile (at the ticket takers gates) on the hour every hour and took the numbers, then went and calculated the results.
Now I always was "nosey-rosey" so I would call my supervisor at least once a day and ask attendance numbers. They "never-ever" knew the answer. However, I also had a friend (supervisor) in RIDES. He "always" knew the attendance numbers. HMMMMMM...
Of course "as employees", we could ask the days attendance as we was clocking out, and always receive an answer.
Now realize that is how SFSL operates to its employees. I have no idea how the general public can obtain attendance numbers from SFSL. --- I do not know how certain people obtain SDC attendance info either. However I imagine the internal workings at SDC gather the numbers in a similar way, how they release that info, "Im clueless".