Why does the hair in my bikini area grow so insanely fast?!?

From talks with other people, this doesn't seem to be a problem for them but I hate shaving! And no matter what, I can never get a perfectly smooth shave. Also I can shave down there in the morning and by the late aternoon/night its already prickly. Nothing works, razors, depilatories (nair, veet), waxing, I can never get results that last more than a day! Any suggestions to solve this? Any belifs as to why this happens? Now, my hair everywhere else does grow "fast-ish" but nothing is like the hair on my bikini area! Help please!