Mature and intelligent enough to outsmart STDs and pregnancy. Yep the science checks out boys. Condoms become useless once you turn 18.
To be fair condoms are a pretty terrible method to prevent pregnancy. As a secondary method it's fine, but if it's the only thing you use well don't count on not having a baby.
I remember a study that rated the chances of pregnancy for every contraception method over a 10 year span and condoms very slightly better than pulling out, but still something like 30% chance of getting pregnant at least once in that period, while stuff like the pill was well under 1%.
So if contraception is your only objective in a monogamous relationship, then condoms are most definitely not your best bet.
If you like to sleep around then yeah, there doesn't seem to be anything better to prevent STDs at the moment (though I'm curious about the actual success rate of condoms over a long period of time on that as well).