Where are all the other kids who don't talk???

I am an SLP.  I know more about disordered speech than typical.  I work in an extremely poor school.  We always joke at school that someone will say this kid is really smart and we really mean "average intelligence."  So many of our kids are low.  So so so many.  We took the boys to a mall indoor play area today.  They love it.  I notice none of the other parents even get up.  They sit in the cushy seats surrounding the play area and they let their kids go at it.  I end up with every kid around me, asking for help, joining in our ring around the rosie game, looking to me for praise, and I am so pissed at these parents.  They are leisurely drinking their coffees and I am sweating, out there playing with my kids.  Alex tells me to balance it which I need to work on, so going out for a bit, then watching, but it is so hard to send your kids out there who can't be understood by others.  Landon was chasing this little boy and then they were pushing each other on the slide.  The boy was very verbal, but he pushed Landon one time, so hard that he almost fell down the stairs.  Poor baby burst into tears and it took 2 minutes before the mother came out and then put her child in time out.  I look around and I don't see any kids who can't speak.  I see not one.  I saw kids less than Logan speaking.  Where the hell are all these kids?  I know speech delays are common, I get that apraxia is not, but are these kids hidden?  Do people not take them out?  Ugh.  I am always looking around, trying to find another kid like us, so we are not so alone :(