It's because they want to have their cake and eat it too. They want people to just never have sex unless it's with their spouce of the opposite sex with the intent of having a child. But laws and policies can't be made around an ideal. If things were ideal, we'd need no laws because no one would do things that we'd want to outlaw. Laws need to be made with reality in mind and the reality is that people will have sex. The outcomes you can choose from are: 1) people are well informed and use proper contraceptives, the best choice becasue it is the cheapest, requires the least medical intervention, and stops STIs too. 2) people get abortions every time they get accidentally pregnant, not ideal but still better than 3. 3) people are having children like crazy, a lot of them end up dying and/or people are constantly living in poverty, disease runs rampant and societal, technological, and scientific advancement are stunted.

But people act like there's a magical 4th option where everyone just has religious ideals and follows them to the letter (when told to by their pastor) and no one ever has sex until trying to have kids. These people should never be in charge of policy making because they make objectively stupid policies with objectively stupid thought processes.