I hear of back in the day when school days began with prayer and nobody complained, but you'd think something would've been done about it early on in American history.
Here’s a look at the arguments, in a paper from shortly after the Engel v. Vitale decision.
It took a long time for non-participants to take the significant social risk of speaking up and ultimately going to court. And in many parts of the US during its first 100-odd years, everyone or almost everyone did identify as Christian. Christian institutions were granted authority over Indigenous people (especially children) who had exhausted their capacity to resist. Religious instruction in school was considered to serve a public purpose.