:: Why would you pick classes that wouldn't transfer?
Simple -- you have basically 3 degree options in Community college -- Associates in Arts, Science, and Applied Science. The applied degree consists of classes that generally don't transfer. However, that degree does prepare you for the work place after 2 years (assuming you can find a job that doesn't think of an Associates degree as a failed Bachelors). Whereas the non applied degrees won't give you any job skills, but only prep you for a 4-year college. In any case, it is recommended that a student work with the target 4 year institution, to determine which courses to take at the local community college, and not do it blindly.
However, this is actually a bigger issue. A lot of the high school classes are dumbed down enough that they really don't prepare students for college level courses. So often times students have to take 1 - 2 semesters of additional prep work classes before they can jump into the real college classes. This can even be true if one took "college prep" classes in high school (depending on how crappy the local school district is).