That’s because there are no “low-margin” wage workers, who make large figures in gross salary, but also have extremely high “costs of earning wage”. I can’t think of any wage worker who would fit this bill. At best, this could apply to some self-employed people, but they can just incorporate. Maybe it would also apply to very low-wage workers, if you consider food and housing as cost of revenue, but then again low wage workers already pay basically no income tax.
That's not really true. There are and have been many states, provinces and cities where my line of work is rewarded with high pre-tax pay, but the cost of living in those places (especially housing) makes it uneconomic.
