As I said, you have to go through proper channels to get a monopoly in the US. If you don't, the penalties are harsh. But if you do, the benefits are enormous. And just like you can't go into a smoke shop and ask for a bong (it has to be called a "water pipe"), you can't call it a monopoly. It's a "government contract."
Also, legal remedies are typically only taken when there is an abuse of a monopoly. It's not illegal to have a monopoly, it's illegal to use it in ways that gain you an unfair position that you wouldn't otherwise have. Of course, I agree that problematic monopolies typically only arise due to government interference. But the solution to problems created by government being more government is nothing new.
If I am the only maker of gerbil hearses in the market, I have the monopoly. Legally, that doesn't mean anything needs to be done about it unless I use my monopoly position to lock out new entrants or to destroy competitors to my small-mammal-vehicle tire division.