I know electoralism is unpopular here, I apologize in advance. Has any party, while campaigning for workers' votes, ever offered to tax unionized workers' wages preferentially; like an excise tax against non-union shops?
I noticed that you can’t deduct, as a business expense, any amount of money spent in furtherance of a crime. Why can't you change tax law so that only a quarter of non-union wages can be deducted from a business' taxable income? (Of course you could also define what a union is to prevent "straw unions", ostensibly controlled by capital.)
In a [insert capitalist country here] where this would even be possible, you'd probably have the political will of the people so solidly behind you that it would be better to just nationalize everything you could get your hands on. Its not like there'd be anybody strong enough to stop you.