Age verification on liquor product websites really required?

If you visit any alcohol/liquor product websites, you are sure to see an age verification form. What good does this practice do? I am sure any 14 year old who comes to these website is not exactly stopped by these forms. So why have them there? I think its to do with showing that a company is responsible and doing whatever little that needs to be done. In this case it costs you 1-4 clicks extra depending on the website.  But the question here is, why does the whole internet behave the same way even when you know that a practice makes no sense?

Here are a few websites I’d checked out to see who was verifying what. I must add that liquor companies make brilliant websites.