If you want to buy something on amazon you need to get an exchange who offers steemdollar trading(Not a lot of exchanges are offering it) and only threw steemdollar -> bitcoin -> local currency ... takes some time for sure. You can not compare steem dollar with banks, again!
And why not directly keep bitcoin instead?
Yeah you have a point with the first questions if you take a long time trading. Guess I have just been trading a lot so no big sweat. But hopefully this will get easier and easier (shapeshift perhaps:? )
Because steem dollars are pegged and Bitcoin isn't?