Spanx

I have never worn Spanx before (I am not a big fan of tight things), but I know people that have.  I once read a hilarious story about a woman trying to remove her spanx in an airplane bathroom.  So I was looking at an add for Spanx today and the model they were on was a perfectly slim and skinny girl, who had no need to wear spanx and probably never would.  Why do they not put it on a model that really would wear spanx so that the average woman can see what it would do for her....common sense right?  Maybe it is just good advertising for people who look at that model and think...yeah I want to look like that. Beats me, just struck me kinda funny.