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.)