I was mistaken, I thought it was a California state wide thing but I guess not.
Either way, your statement about the top 10 CA high schools is false. I attended Granada Hills Charter and San Marino high school (#1 and #7 respectively) and both do absolutely require community service. San Marino requires 40 hours over four years [1] and GHCHS requires 20 hours per semester [2]. A friend at Miramonte High School didn't have to do any community service but I recognize many of the schools on this list and can confirm they require community service. Searching for "graduation requirements" just gives you a list of credits you need but doesn't include community service or disciplinary rules for graduation.
Looks like Saratoga High also has a community service requirement. Other than that, I can't find any others on that top ten sublist (e.g. Canyon Crest explicitly states it doesn't have a community service requirement [0], Lynbrook states that community service isn't a district requirement).
And to be fair, I don't think charter schools should be lumped in with the rest of the public schools, but that's probably just my opinion.
I will cede to your first source, but your second source is specifically for CSF membership at Granada Hills, which doesn't look like it's mandatory for graduation.
But sure, it looks like my naive search approach is inadequate, as it for the most part brought up credits (as you mentioned).
Either way, your statement about the top 10 CA high schools is false. I attended Granada Hills Charter and San Marino high school (#1 and #7 respectively) and both do absolutely require community service. San Marino requires 40 hours over four years [1] and GHCHS requires 20 hours per semester [2]. A friend at Miramonte High School didn't have to do any community service but I recognize many of the schools on this list and can confirm they require community service. Searching for "graduation requirements" just gives you a list of credits you need but doesn't include community service or disciplinary rules for graduation.
[1] http://www.sanmarinohs.org/apps/pages/index.jsp?uREC_ID=2241...
[2] http://www.ghchs.com/UserFiles/Servers/Server_20226865/File/...