I have used them for the last 3 years & the majority of the mothers there are middle class. If they didn't go, the places I go to would be almost enmpty.
I use them a lot and my children have got a lot out of the classes/events there. We may not be poor, but our household income has dropped a lot since I gave up work to bring up our children. It is very helpful to be able to take them to some free classes and meet other local families.