I guess government could argue there are services they need to do to for your property that they need to be paid for.... like pavement and road in front of it etc.
If the government has to enforce copyright law, might as well make the copyright owners pay for it, they're the ones who want the law enforced.
The one tax that irks me the most is the property tax. Why? Because a property tax on something tells me that I don't own that item -- I am simply leasing it from the govt. as long as I continue to pay the property taxes.
While getting more responsibility from copyright holders has some appeal (darn you evil Disney!), property taxes on intangible ideas would be very risky in that it would be an easy way for governments around the world to appropriate ideas easily.