I can't begin to fathom how some men do not care about a women's past. Do they not care that their LTR (women they have promoted and deemed special enough to provide comittment to) has fucked a lot of men before them?

Sometimes I hear men saying, they don't care or they'll never know anyway. Firstly if they didn't really care then why don't they want to know the truth? Secondly, it's very obvious when a girl has been with a lot of guys, even without telling you. Why do some men not care?