|MadSci Network: Physics|
My area of expertise is space, and not physics, so I'll only be able to answer your question from that standpoint. If you want to know more from a physical prespective, you can re-submit this question. That said, here's the info.
The space shuttle is simply very hard to land. The landing strips for space shuttles must be extremely long and almost perfectly flat for the shuttle to safely land. Even with that nice landing area, they still need a huge parachute to slow them, and a large land crew to work on it, doing things like cooling it to make sure that the astronauts can safely land. This is because for many reasons a space shuttle is not at all like a plane. The only similarity is that they are both designed to be controllable in the air. But the space shuttle, unlike a plane, is designed primarily to be in space. Its large, squarish, massive, and bulky design is optimized for travel to and spending time in space.
First of all, the size and shape of the shuttle makes it very hard to land. The side of the shuttle is more flat than on other planes, and that makes crosswinds (which can be quite powerful at the height and location shuttles come in on at Canaveral landings) that much more effective at pushing the shuttle.
Also, the space shuttle is extremely massive. Although there are planes that are about its size, they do not have the same mass. This is because they don't have the hulls and equipment designed to support the lives of several people in outer space for an extended period of time. The pressure of very high altitudes that some planes cruise at is nothing compared to the vaccuum of space in terms of the engineering required to withstand the internal pressure's push to escape. All this means that the space shuttle is that much harder to control in the air, because its less responsive. A VW bettle changes direction much more easily than an 18- wheeler loaded with produce.
If this information isn't enough, please send us the question again, because I am positive that there is more information on this topic than what I have presented here.
Try the links in the MadSci Library for more information on Physics.