Perhaps between the ages of 13 and 16 that is the right behavior. But a child of 10 or 11 is in no position to be left alone with friends at the mall. Friends are not dependable at that age, and the child him or herself often has no common sense in order to avoid trouble.
I believe that young kids between the ages of ten and thirteen should not be dropped off at the mall without adult supervision. That is way too young. They can get into trouble too easily. Malls are also not meant to be babysitters. Kids should be at least 16 before they go to the malls by themselves.