Jewish Universities: Yeshiva U & Touro College ✡️🎓

“Those Frum schools that do that because of the parent clientele. It’s not ideal. It’s usually Kiruv types of schools!”

In my experience, it has nothing to do with ‘parent clientele.’ It has do do with the cost of opening/running a school in a small frum community.
It may not be your ‘ideal.’ but ideal for the particular community.
Most OOT communities don’t have Kiruv type of schools and Non-Kiruv type of schools. They have an orthodox day school, period. Many run by Chabad, others part of Torah Mesorah
The Day school in the New Haven area that is mixed gender in the primary grades has existed for almost 75 years. Their Girls High School for 50, BUT there have been 4 Boys high Schools in the past 50 years that have failed. Families want their little kids and girls at home, they are willing to send teen boys away for high school.

“First of all, you didn’t post the whole Teshvuah,”
Health, you can see the whole Teshuva from the link – I just checked.

“I wrote “usually”!”
You were responding to ZD who wrote that there are schools that are coed for financial reasons. I thought you were arguing with him, so I was giving an example of a case where he is right.
But I guess I’m not disagreeing with you if you wrote “usually”, and I’m sorry if I gave the impression that I was.

In any case, it doesn’t contradict your original point about Frum schools being different since it started out coed, and has actually become less coed over the years instead of the other way around.