There are many people who want to attend an authentic service and belive in hashem but for whatever reason dont want to follow all Halachas, They might attend a Young Israel and they are welcome to go there with open arms.
If MO schools take Non-frum students , which they do, you cant expect them all to be frum after school, The Charedi schools do not usually take non-frum kids. At least some of the non-frum kids will become frum so they school is a sucess
Those are both excellent points, demonstrating that the raw numbers, without understanding the context, do not necessarily reflect failure to keep people frum.
Regarding the second, I would ask richashu: how many of those 150 came from “shomer shabbos and shomer kashrus” homes?