I know that LARC is meant to be more reliable and have a lower failure rate than the pill. I know that's why GP's and family planning nurses, etc often heavily push LARC and do the hard sell to people on the pill.
I can actually see why they would be more reliable as there's no room for user error with LARC wheras with the pill there is. But AIBU to think that the main reason (and maybe only reason) LARC is more reliable with a smaller failure rate is because there is no room for user error?
So say you have two people, person A has the implant, person B is on the pill. However B always takes her pill religiously - she never misses one and always takes it at the same time each day. She also never does anything that might effect the reliability of the pill and has never taken medications that might effect it. She has also never vomited or had diarrhea throughout her time on the pill. However she knows that if she ever did get D&V or take antibiotics then she would abstain from sex during this period.
With that in mind would person B still have a higher chance of their contraception failing than A? Maybe I'm being stupid but I really don't see how that would work.