You're right to highlight that many women put up with far too much, but in many cases it isn't simple at all to leave. If you're working and just married to a lazy misogynist dick then, yes, I guess it is relatively simple to leave. However if you're married to a lazy, misogyist, dick who also controls your money, has isolated you from friends and family, shattered your self confidence and self belief over a long period of time, appears charming on the outside so no one believes what an arsehole he is, it's very hard to leave.
How do you get the money together for somewhere else to live when he takes all the money or keeps getting you fired from all the NMW jobs you managed to get? There are far too few shelters for all the women who need them and they're not actually safe. Where are they to live? It's easy for some people to facetiously say they'd rather live on the streets, but would they really, with the very real risk of rape, abuse, lack of basic toilet facilities, no food etc.? Friends may actually know or suspect some of what is going on but in reality, they're very reluctant to intervene and, unless they're rich, what support can they actually provide? They don't have room for you to live with them, they can't loan you money for a rent, they can't keep you or themselves safe when he inevitably tracks you there, breaks down their door and attacks you in front of them.
And what if you have kids? The courts will grant the father access no matter how violent he is or what sort of environments or people he exposes the child to. At least at home, the mother can be the punching bag and main focus.
Until you solve all of these problems, women are more likely to stay than leave.