These people quit their jobs because they were happy with their child benefits of 500 per child. This given fact, that they quit there jobs, makes me suspect that they would rather choose the strategy of increasing their salary by their number of kids than by working.
If the question would have been 'what would you do', I think I would have quit my factory job as well, actually.
These people quit their shitty jobs because they are no longer forced to do them for the sake of survival, and now have more time to spend with their family, which–I guarantee you—is more valuable than whatever they were doing at work.
Why do you think wanting to quit your job is anybodies fault, but the employers?
What you suspect of other people tells a lot about you, and very little about other people. I would be careful with that.
While I second mrottenkolber that your guess is highly stereotypical, the intention of the polish state introducing their "500+" program seems to be exactly that: increasing the birth rate.
Do you have a source on that, or do you think lawmakers might also be concerned with the well being of children, mums, dads, single parents, young parents–no matter how many children/parents there are?
There are various (english) news articles (for example [0][1]) and also a paper for the European commision [2] (so called ESPN Flash Report) claiming that.
But besides those sources there is also the fact that the child-raising benefits are only unconditional from the second child on, for the first child there is a maximum monthly income to get it.[2] If the main goal was the well being part, then this would not make much sense.
The interesting question is what would happen if it was for everyone and not just those with children. Do you think this would be a bad thing?