In the present situation a person pays union dues to his union each month.
This monthly amount is totalled to a yearly one and is then applied against his taxable income which is then reduced by this amount.
This means he does not pay any union dues.
However, some money has been paid to the union each month. Since he does not pay any union dues somebody has paid.
That somebody must be the taxpayer!
This indicates that the only people who pay union dues are the taxpayers not the union member.