You can be an adult but not mature. A doctor should at least be professional and take their profession seriously, which in part is to do no harm.
First of all, planning one’s future and taking into consideration troubles that may lie ahead
is mature. You wouldn’t call someone getting fire insurance immature, even if only a fraction of homes are lost due to fire.
These doctors who are performing these sterilizations are taking their profession seriously. They know that there are people who do not wish to have children. Full stop. They know that unwanted children may be aborted, or left in a system already overcrowded with such children, or possibly live in a home where they know they’re not truly wanted. Yes, sometimes an unplanned pregnancy can lead to great love, but you certainly can’t ignore the many children who aren’t as lucky.
As far as harm, we simply have different ideas as to what that means. There are women right now getting gene tested for certain types of cancers. In some cases, those women who are positive for certain genes that could lead to breast cancer are having their breasts removed. Would you consider that harm as well?
A young woman wanting to be sterillized ‘just in case’ she happens to be raped and conceive is clearly thinking irrationally. Notice that it’s not because she doesn’t want to have children at all, full stop (but even then who’s to say she might not change her mind?) but out of fear of a fairly rare occurrence.
Again, just because it is a rare occurrence doesn’t mean it won’t happen. We only live once and if someone wants to take extra precautions then I can’t fault them on it.
Now if she’s willing to be sterillized, it’s hard to imagine why she would be against taking contraceptives to avoid the risk of pregnancy (neither of which are always 100% guarantees, as an earlier poster pointed out), which would remove the fear but at least leave her the possibility of having children, should she so choose. Sterillization is supposed to make that virtually impossible.
You said it yourself. Neither is 100% effective. Combining both brings a person that much closer to 100%.
A person living in a gated community still locks his doors.