My public elementary school (1960s) always had meatless Fridays: fish sticks, "tuna boat with cheese sail," macaroni and cheese. No shocker, the district was mostly Irish and Italian. And some Jewish kids, who, if they practice their faith, know a lot about fasting and abstinence.
I think it's called being "sensitive" to the local culture, right? But nobody used that expression then. Someone would kick your butt if you did.
When I was in high school in the early 60s, our cafeteria served fish on Fridays. I doubt there were more than a dozen Catholics in the entire school system.
No one complained about it despite the fact that the vast majority of students were Presbyterian, Methodist, Baptist or Pentecostal.