You might end up paying 1.00 BTC, or 0.6 BTC, but it still works out to the be same in USD/AUD/<currency> (numbers made up for example)
No one wants to use a currency that swings 20% in hours of trading. Hell, that's prob 4-5x the margin on a lot of computer hardware.
> The net amount that BitPay merchants receive is equal to the gross amount (USD) of the order submitted, minus our fee.
> It does not matter how many bitcoins we collect, how long it takes to collect them, what we can sell them for, or how long it takes to sell them.
(not affiliated, just said the same thing last time this came up on HN)
Who's handling all the instant real money conversions, and why wouldn't they just transfer the real money between accounts directly rather than converting it?