Why is moonshine illegal?
First of all, please note that making your own alcohol is legal in most states so long as you do not make too much of it.
To the extent that it is illegal, some people would claim that it is because the government wants to be sure that it gets its tax cut on everything that gets produced in the US. That, to me, is a bit cynical. I would argue that moonshine is illegal for health and safety reasons. People making their own alcohol might not take the proper precautions necessary to ensure that what they are making is safe for people to drink. Legal brewers get inspected, home brewers don't.