If I Acquire euro's with USD on my visa, or a pre loaded euro Visa card and the euro goes up, and I buy things, does this attract the same tax?
I would not say it is the same tax. Your gain through currency rates is taxable as ordinary income, or dependent on situation possibly taxed per form 6781 section 1256 for "currency contracts" which I believe is applicable for a lot of currency trading. To the best of my understanding, BTC is taxed in the following manner:
Mining: You pay ordinary income tax on profits you get from mining.
trading: You pay long or short term capital gains based on the profit or loss from the trade.
More foundational though, the Govt has lost the right to Tax, this creation in this way or us. The Govt has lost the right to tax per se as it fails to provide sufficient quid pro quo for the Tax burden it imposes.
They didn't lose it, per constitution the government never had the right to tax income. However it has been doing it since the mid-early 1900s, and its not going away, though I would agree with you in that it is very difficult/almost impossible to enforce tax law on bitcoin transactions.
All tax.