Yes, that's the point, isn't it? It's far easier to just take a pill or put a condom on than to understand and monitor a reasonably complex scientific process. You need a good understanding of biology, more than the average person.
You are all correct, once again, medical professional.
did you know 40% of women misread pregnancy tests? All tests are 99% effective, but when left for an average person to interpret they have to take multiple or mis interpret the results. Example of misquoted statistics to sell products.
The pill is 98% effective you take the medicine at the EXACT same time everyday, but if you are off by a few hours or have digestion issues, vomiting or diarrhea. It is not absorbed properly, and you are not protected for 7 days ( assuming continued accurate use.)
That's not even mentioning that sperm survives in the vagina for up to 7 days, so while you might have sex when you are not fertile, the sperm is laying in wait for that egg!
The most effective birth control are 'set and forget ' methods. IUD, Implants etc as there is no human error.
Hope that sheds some light on the statistics, clinical studies and real world studies have a huge variance in birth control.