Most people get caught because of some other issue. It could be that you needed a home repair, had guests over, etc and someone saw something and reported it. It could be that you're investigated for some other issue. It could be that someone posts something online or in a text and you're later investigated for something else.

Yes, there's a very small chance of getting caught doing a number of things if you do it right. Even the overall murder solve rate (which includes non-prosecutions for weak cases or lacking evidence) is only about 70% in the US, and I imagine that many of the ones caught don't do it "right". But it's the value proposition that matters. Is it worth making a couple of gallons of alcohol that I could legally purchase for a few hundred dollars or less when there's a small chance of me going to prison for years and owing tens of thousands in fines and fees? Remember, we don't have a justice system, but merely a legal system. They would not hesitate to ruin my life and my family over a few gallons of illegally produced liquor, as they've done it to others.