Why do people ask store clerks if they "work here," especially w

Court House - Why do people ask store clerks if they "work here," especially when the employee is emblazoned with store logos, name tags, aprons, etc.? I guess people today don't notice and can't ask a simple "can you help me?" Also, why do customers throw money at the store clerks? That is so rude! I see this a lot and feel sorry for the employees. They are human too.