well, there is the cultural difference that western cultures do not seem to prize long hair as much as eastern.
But also, as mentioned before, most hair just won't grow that long. Most women find their hair, no matter how careful they are with it, and how healthy it is, will not get much past classic length (just below the bum).
Thats why long haired beauties, be they Eastern or Western, are such a novelty. Because it doesn't just happen.
I'm hoping to get my hair to my mid-thigh, but I don't know if it will grow that long.