Question: Why do most clubs have an age limit of 21 and over but all clubs have alcohol? 

Answer: Clubs that are 18+ and serve alcohol are a bit more work for the bartenders because they have to check id's everytime, but in a 21+ club you get you id checked at the door, and then when you want drinks you don't have to show ID again.
This question from the Yahoo Q&A forum is categorized in the topic: Entertainment & Music