That used to be the case. My late wife had a degree in History and a minor in English Lit and took four education course her senior year to become a licensed teacher. I had a degree in Environmental Biology and a minor in chemistry but took some education courses because she wanted me to be a teacher. I quickly found out I wasn’t cut out to teach kids but enjoyed doing EPA/OSHA training as part of my working in the environmental field.
I believe it was in the late 80’s when they started giving out degrees made up of biology for educators’ type classes.
Yes I believe you are correct about the biology (other subjects too) for education majors and the timing (if not sooner).