If you think charging a fair amount for advertising is a "tax" you are beyond reason and beyond help. Care to take a poll here to see how Freepers judge this one?
I'd side with CNS in that poll.
Advertise on a private venue and the amount charged is a rate.
Advertise in a government-operated monopoly created via the force of law, like official state highway signage on an Interstate freeway, and it's a financial charge (fee or tax, take your pick) required from and for the government, and therefore is a form of taxation.
Your logic means everything that costs money is a tax.
Your deduction defies logic. Money I pay voluntarily to a private enterprise is commonly called a rate, a fee, a price, a charge. Money forced from me by the government to obtain a place in their system, be it drivers' license "fees" or "permits" to be included on generic freeway offramp signs, profits the government and therefore is a tax.
Choice voids your trickle down, businesses-don't-pay-taxes-but-pass-them-on-to-the-consumer justifications for calling that a tax.
Secondly, let's move that signage 50 yards off the road to private property. Is that billboard a tax? Only in your distorted view of taxes. There is no difference; the property owner charges a fee to advertise on their property. The government owns the freeway right of way and therefore plays the same role as the private property billboard.
But, if you want to call it a tax, implying its costs are forced upon us, be my guest. There is clearly a distinction--that primarily being choice--why do you not wish to acknowledge it? Romney haters?
Could you at least consider the idea that the government is selling space on the highway signs? The buyer of that space does it voluntarily. Not every single business near the exit ramp chooses to purchase the advertising space, so it is a buy/sell transaction, not a take tax transaction.