I don't like unions either. But if you outlaw them, you'll end up outlawing religion, groups like us FReepers and the Boy Scouts (although they are already under attack.)
The First Amendment protects unions, and I can live with that.
For most of the history of the US, unions were illegal. Union meetings and work actions were broken up by police and national guard troops, their leaders arrested, members fired from their jobs. That was during the period of America’s greatest increase in productivity and world power. And that is how I believe unions should be treated today if we are to regain the economic power we once had.