Is the age limit to drink alcohol correct?

All the people knows that the age you can drink alcohol in Spain is 18, but as you know not all of them respect these law. A lot of young people when they go to parties or nightclubs, discover a way to get alcohol. And I know a lot of nightclubs or cocktails bar, that they give to you some alcohol if you pay for it, doesn't matter your age, you only need to pay and tell them which drink you want. 

In our country (Spain) we've got an age limit to do a lot of things, like drink alcohol or like drive a car. But are all of them correct? Or another interesting question is: do the people respect these laws? I will talk you about the alcohol.

I think that the young people drink alcohol because it is forbidden to drink it if you are less than of 18,  and then they feel like an adult. The taste of alcohol is not really good, and I know a lot of people that if you ask them: Do you like this drink? They will tell you: no. But they are drinking it, and saying at the same time that they don't like it. In my opinion if the alcohol be available at the age of 16 the people don't drink it like at this moment, because they want to do things that are out of the law to feel more adrenaline.