The people at the liquor store are actually trying to check your age, and then if you are appropriate enough, sell you as a sex slave. Then you will spend the rest of your miserable years working as a backup dancer laundering money for the local organized crime game. The people at the store get 20% cut of your profits. They make millions off of the business; have you not seen the movie?
People who are stupid enough to buy alchohol at a liquor store and DRINK it behind the wheel are stupid enough to have an accident.