I am not a doctor but from what I hear most people treated for alcoholism do not have a pure "physical dependency" as compared with other drugs such as heroin, etc... And it is more habitual and psychological. Not trying to lump it in with the Starbucks addict by any means but I think it is in most cases somewhat different than other drug addictions. It is definitely a serious problem though.
You're thinking marijuana, which doesn't appear to have extreme physical withdraw symptoms. Alcohol does create physical dependency, and the withdraw symptoms are quite unpleasant. From WebMD:
"Alcohol withdrawal symptoms can begin as early as two hours after the last drink, persist for weeks, and range from mild anxiety and shakiness to severe complications, such as seizures and delirium tremens (also called DTs). The death rate from DTs -- which are characterized by confusion, rapid heartbeat, and fever -- is estimated to range from 1% to 5%."
That said, physical dependency isn't really necessary for addiction to occur it just makes recovery that much more complicated.