The world is steadily getting flatter and better connected. Our money seems to be just points on our bank accounts and beggers will soon have to have some sort of apple pay system just get get a dollar off some one, not to mention the hard working strippers. A generation or so ago and everyone traveled with travelers checks and had secret pockets in their jackets, wallets and backpacks to hide a hundred dollar bill for a rainy day.  Now months go by without a visit to an atm or pulling an actual dollar bill to pay for a purchase. Most credit cards and debit cards will allow the user to buy whatever they want in whatever country they want without any additional charges. Even at the cost of some small exchange rate charges, the user gets the safety of insurance provided by the credit card companies. No having to keep up with different currencies change or exchanging notes when entering and leaving the country is a bug plus as well. There are some minuses such as if you lose the card then you are at the mercy of waiting to get a new one but at least you are less likely to lose your money from your account. Weighing the risk is up to each individual but most travelers will whole heartedly agree that traveling today on card is the best alternative. Here is a list of the countries that make it the easiest to travel without ever actually touching a coin.
Belgium
France
Canada
United Kingdom
Sweden
Australia
The Netherlands
United States