Obviously you could write several books on this. I'm going to try to condense it into a few paragraphs, aimed mostly at US girls. Girls abroad already know a lot of this.
1. Our families are often dysfunctional and split apart, so we don't learn respect for women from our family members. Often we hear only negative evaluations about the other sex from BOTH our fathers and mothers.
2. From a pretty early age, most girls are taught to USE sex and attractiveness to get what they want. Their mothers encourage them not to 'waste their time' on guys without money and status.. So,, for the most part, they don't.
3. By age 16 or so, many girls are, ahem, 'dating' guys in their 20's or older, and won't even look at their classmates...My high school was pretty typical. When classes got out, there was long line of cars at the gate. Some were parents, but many were older guys picking up their high school 'girl friends.' Today, we'd call them 'sugar babies' mostly. We didn't back then, 20 years ago.
4. In college, ditto. Many of the girls were, ahem, 'dating' MUCH older guys, weekends in Paris and the like....
5. Out in the working world, even worse. Girls were quite often sleeping with the boss, and wouldn't have anything to do with guys at their own level. Even girls not into that scene were envious of the ones who were 'liberated' enough, and pretty much identified with them. Heaven help you as a guy if you spoke out about it at work--they'd mostly all jump on you.
Now, of course, the above doesn't apply to the large numbers of immigrants or second-generation girls, mainly Asians and Latinas, who are mostly still pretty 'old country' ,and don't go in for the informal prostitution that dominates relationships in the mainstream in the US. And of course, even among the mainstream, plenty of girls are still 'old fashioned', and those who get married young usually don't swing in this way, regardless of ethnicity...
And guys generally respect their mothers and grandmothers, because this kind of attitude was much less common in earlier generations, and more women got married young and didn't even think about other men after they were married, for the most part.
But in the mainstream culture today, this is what most guys think of when you ask them if they respect women. What honest answer do you expect them to give? A lot of guys aren't going to answer that question, or will evade it, because the answer may get them in trouble.
But their actions will tell you what they think. And can you really blame them if their real answer is that they have little to no such respect?
Respect isn't given unless earned.....