Yes bitcoin is taxable. Not by means of the government is taxing but I guess that the miners were the one who are asking for taxes. The confirmation is dependable on how much btc you spend. If you will spend the high amount in sending then the confirmation of your transaction will be fast.
I have also thougt about that idea. The government couldnt manage bitcoin so i think there still are people who are asking for taxes for them to be able to have their profit and for the system to function well. This idea really helped me to understand more the system and I couldnt agree more about it. It is true that sending high amount has a quick process of confirmation of transaction.