Of course there are more alcohol problems. That is because it's legal to drink it from a young age.
You cannot compare the problems caused by something that is perfectly legal and something that is illegal.
There is a huge number of people who will not touch or try drugs because they are illegal.
There's also the question of social acceptance. Booze to an extent is socially acceptable whereas in the main, drugs aren't.
Wossy, these people who drink alcohol at a 'young age' are probably breaking the law especially if they're drinking it in a public place (like in a park). But that doesn't tend to stop young people from doing that anyway.
And of course you can compare illegal drugs and alcohol because both can be used in exactly the same way; both affect the brain.
As to what's socially acceptable or not depends on what circles in society you mix in. Drugs is obviously acceptable at a social level in the circles Ritchie mixed in (or were), but they're NOT acceptable in mine.
Given alcohol is probably the UK's No 1 cause of social problems, I think it's hypocritical to get all high 'n' mighty over illegal drugs. Remember, just because something is legal doesn't automatically mean it's right and moral. An example is the prohibition in the US; at one time alcohol was illegal, then it was legal, which just goes to show that just because something is against the law doesn't automatically mean it's also immoral. Unless of course you base your morality purely on the law, which would be daft. Nazi Germany (Godwin's law withstanding) had some laws which most right-minded folk would find immoral.
And all prohibition did was make gangsters rich; it didn't stop people from drinking. I think illegal drugs is like that.