Because even if someone manages to get one or two of them right, they seldom get them all:
Hacker n. 1. Originally used in the 1970’s to refer to someone who was such a good programmer they could write code without referring to reference materials. This was a much bigger feat back then, when you consider they were essentially working with a text editor. 2. In the eighties, it became anyone who could gain access, through physical or social means, to a computer system they had no permission to be on. They were usually not destructive, and were simply “counting coup*”. 3. By the 1990’s, the term came to refer to any person doing something not legal with a computer, but for the most part it dropped the social engineering aspect and relies primarily on computer knowledge and use of software.
Phreaker (a.k.a Phone Phreak) – n. 1. Someone who through use of technology such as a tone-generator or social engineering manages to obtain free telephone service, usually through public pay phones.
Crackern. 1. Someone who is primarily known for breaking the copy protection on software.
Script Kiddien. 1. A person with little or no programming knowledge or skill, who uses tools constructed by someone else to launch destructive or disabling attacks on computers over the Internet.

*Counting Coupv. 1. Associated with American Indian Plains culture. A ritual stick is used by a warrior to touch (not kill or maim) an armed enemy. transfers highest honor and status to touch an enemy who has weapons while you are only armed with a ritual stick.