Can you name me any transaction that would not be taxable? All commerce is taxable.
Your calculation is not quite complete. The only way you would owe $1 on your coffee is if you had realized a huge profit. You owe a percentage of your profits. Lets say it's 20% (it could be less or possibly more). So if you bought a bitcoin for $1 and then it rose in value to $5; you owe $1 in tax on the gains. That is still a 300% gain after taxes. I would definitely enjoy drinking that cup of coffee.
the amount of taxes needed to be paid is not the point.
its not reasonable to expect people to start looking up what the exchange rate was when they received their bitcoins just so they could buy a cup of coffee without breaking the law.