Most of countries consider Bitcoin as an asset or intangible property ( as by IRS ). Bitcoin's treatment as an asset makes the tax implication clear. However, taxation on bitcoins and its reporting is not as simple as it seems. For starters, it is difficult to determine the fair value of the bitcoin on purchase and sale transactions. Frequent traders and investors could use "first in, first out" (FIFO) or "last in, first out" (LIFO) accounting techniques to reduce tax obligations.
Well it's complicated but I think the best way to include taxes on Bitcoin transactions would be to add them up to the miner fees and charge them per each transaction that moves over the blockchain but I don't know how practical this could be since we are all not living in the same country and our laws regarding taxes might vary.
Miner fees are much better than taxes. As you know government taxes are more than miner fees. So it is better that bitcoin is taking fees on transactions etc by miners. I would prefer that miners fees are much better than taxes. Taxes would decrease the demand of bitcoin in a market. If there is no demand how bitcoin will run?