Basically, it can be compared to the Syrian refugees..
The town was built upon the tenets of kollel life and standards, nobody would argue that that is a different lifestyle and value system compared to the avg working family in brklyn, and while there is nothing wrong with the male of the household trying to provide for his family, the fact is that because the current yeshivishe mainstream trend is to learn for a while, the young man who 'goes out to work' is automatically seen as a higher risk to have adopted different priorities and value systems- not because there is anything wrong for being responsible and providing for your family, but because we simply don't know why he deviated from the system. Was he diagnosed with 'mild add' (lol)? Is he just the type to want to be נהנה מיגיע כפיו? He has no support and just can't make ends meet?Just realized that long term learning not for him? Or does he disagree with the fundamentals of a Ben Torahs life, and wants to pursue a totally different lifestyle?
Additionally, even when he truly would like to stick to a Ben Torahs lifestyle; in todays working environment coupled with the technology challenges that are much harder avoided when you are out in the world, it's very difficult to determine which families have stuck to the core yeshiva values that is the basic DNA of Lakewood.
Yes, it's true we all grew up in 'mixed' schools with kids from every type of background, but it was very different then as explained above. The working father wasn't a 'chiddush', the learning people were far and few in between. And the Internet didn't exist or wasn't as rampant, so it was much easier for the working man to shelter his family from all the perils of the world.
So basically there is no way to 'vet' the families in question, so the yeshivishe schools (and parents) try to play it safe. That's not to say they have abandoned everyone else on the streets- they have created 'safe haven' schools that have a more open door policy and cater to a variety of lifestyles, but understandably no one wants to go there...
And since everybody wants to do best for their precious children, they hold tight and don't give up until the last min, and suddenly there are a lot of kids without schools...
Just one person's perspective..