It's all neat and supreme until you are coming out of a grocery store with 9 bags and an XXXL pack of toilet paper and realize that your fancy-parked trunk is way over there, in the bushes.
My father mainly parks with the front out and so when I started driving I did the same. Then I got together with my wife and we had children and she has to remind me of this grocery problem constantly.
I'm going to go out on a limb and bet the vast majority of people do. For the typical person going to a supermarket with a car where they can see what is available and looks good just isn't a big task--especially because you usually have other errands to run in a given week.
