Science sucks!

The current trend of media reporting on science experiments as fact about the entire population is really starting to annoy me.

What I want to know is why 14,000 out of 21 Million people is an OK sample size to determine that Australia is a nation of fatties? (source)

Why 13 people out of 6 Billion is an OK sample size to see that brain patterns are different when playing games? (source)

Why 21 people out of 6 billion is an OK sample size to determine that marijuana shrinks brains? (source)

It's ridiculous! The sample sizes are so small that it makes the reports questionable, if not thoroughly erroneous.

It's like looking at the moon and determining all moons are like that. Yes, we used to think that when we could only see our moon, but now we've got the technology we look at more moons and find that a lot of what we used to think about moons is wrong.

When looking at humans, we've got every opportunity to look at millions more than we do now.

So why are we looking at a mere handful and saying "they're representative of the 6 billion of us here", and worse still, bringing in policies and laws to restrict those 6 billion based on not even 1% of that population?