If the feminists who ignore the Equal Pay Act of 1963 signed by President Kennedy still believe men get paid more than woman, why don't companies save money and just hire all women? amirite?

This is an uncommon argument. I'll give it a try. First, it is an oversimplification. The gender pay gap is complicated. Much of this has to do with who gets the promotion and unconscious bias. Also employer based healthcare.

Women go through childbirth which is really expensive and drives up insurance costs and therefore costs to the company.

https://rationalwiki.org/wiki/Gender_pay_gap

The gender pay gap is mostly caused by unconscious biases, women being historically marginalized, and systematic flaws, not individual conscious misogyny. In the past, women were openly paid 50% the pay of men for the exact same job according to Howard Zinn's book A People's History of the United States.