Many people are nationalists. They are gung ho for their country and everything created around that concept.
I could easily see the scenario where I may be out talking about Bitcoin and some meat head speaking up and saying to everyone and to myself "Here in America, we use DOLLARS"...uhh...derr...
I would love to have someone say that. I would ask him to show me one of these "US Dollars" and then point out the bill he pulls out of his wallet is a Federal Reserve Note. A banknote issued by the private cartel of banks known as the Federal Reserve (which is a government entity just about as much as Federal Express is). The US treasury has no control over the issuance of Federal Reserve Notes which are and always have been the private property of the Federal Reserve.
The last time the US has a "US Dollar" (meaning money issued by government) was 1928.
On edit: I guess I should have said 1928 was the last time all the US currency was issued by the government. As late as 1963 silver certs were issued alongside federal reserve notes (if you find one today it can no longer be redeemed for silver that stopped in 1968).
While the administration of the supply of US Notes was under the control of the federal reserve banking system each dollar was redeemable for 1 dollars worth of gold held in US Treasury accounts.
After 1928 the only difference between Federal Reserve Note and Disney Dollars is that the former is issued by a corporation who had the political will and influence to have to codified as legal tender and that later hasn't (yet). If tomorrow the Disney corporation were to get their private money codified as legal tender it could serve equally well as "the" US dollar.