You simply cannot take 70% from the revenue coming from an employee-like agent, yet report that to the government as being that person's income. Not only would that be blatant fraud, but depending on the exact percentages and absolute amount, the employee might have to give all their pay to the government to covert the tax, and even owe some more after that.
In what country are they doing this?
Where I am in Canada, tax deductions are shitty because they come off the bottom of your income, so to speak. That is to say, the eligible expenses are added up and the lowest tax bracket rate is applied to them. You then get that as a tax credit. That's shitty because you paid for those expenses with your post-tax dollars at your full tax rate, but the credit is for a low tax rate.
Whereas a write-off comes off your income pre-tax, and so the benefit effectively operates at the marginal tax rate, and can knock you into a lower bracket.