BECAUSE THAT MONEY IS NOT GOING TO THE GOVERNMENT.
A tax is remuneration to the government. Period. Full stop. Should I hire "an Alien of Extraordinary Ability" I will pay more to the government than I will had I hired a citizen. That is a tax. Should I buy gas in Los Angeles County instead of Riverside County I will pay more to the government. That is a tax. Should the government require me to pay someone a dollar more than I want to, however, that is NOT a tax BECAUSE THE MONEY DOES NOT GO TO THE GOVERNMENT.
Demagogques use the word "tax" incorrectly because they have successfully made "tax" a bad word, so they might as well apply it to everything.