Don't know about Mickey or how corps are taxed on their assets but I assume they are taxed on what they gain from their assets. So if Disney makes $2 Billion a year from Mickey they are taxed on that.
Also, when Eminem dies, IRS will value his estate (mainly image rights, songs and copyrights) and send a bill for close to half of the value.
A person who owns a house and rents it out is taxed both on rental income, and on the value of the house itself.
They say that copyrights are "intellectual property". Let's treat them as such in other respects, not just when it comes to protecting property rights.
Also, when Eminem dies, IRS will value his estate (mainly image rights, songs and copyrights) and send a bill for close to half of the value.