As we all know that bitcoin now are being made as a trading pairs to different fiat money all over the world. And we you go round the world having a good vacation on different countries you do not need to bring more fiat or physical money instead bringing gadgets and connecting to internet is enough to get fiat money after it will be traded to local exchange. In this way there is no need for one to bring more physical money as bitcoin could unify all fiat money around the world as trading pairs.
Bitcoin can be used like that if you like but bitcoin is nowhere close to be used like that for the majority of people, if you want to do that then it is way easier right now to use dollars, you can use a credit card that is denominated in dollars and then exchange those dollars for the local currency and have the same experience and it will be way easier to do that exchange due to the popularity of the US dollar.