You know how you will never be able to repay your mother for what she went through when she gave birth to you? These ladies you are talking to and about are/will be those mothers. Raising a child is not a 9 - 5 job, its a 24 hour job with no overtime, benefits, instant gratification, etc. What she goes through for 9 months, during and even after childbirth is more then you can imagine or fathom. Rather then trivializing child birth, I would think you might appreciate because thats exactly how YOU got here and are able to write what you did.
A woman gave birth to you…something you will NEVER be able to compensate her for.
Yes, she deserves to keep her money if she earns it. Islam says it, Allah swt says it and you dont agree with it?
Regardless of all this, I dont know a single woman who actually exercises all of her Islamic rights by keeping her money and not sharing it. Every woman I know contributes if she works in some way.