It’s not that Harper Auston doesn’t want to attend her 6:15 a.m. Latter-day Saint seminary class. Her friends are there, and the Denver 15-year-old likes starting her day learning about Jesus.

Shauna Hostetler, who taught seminary in West Palm Beach, Florida, from 2012 to 2020, estimates she “easily” spent $1,000 a year for classes of 15 to 30 students. A top expense was paper and ...