Handling a foreign currency is a lot of overhead, you will only find this accepted in locations where it is quite common for people to not have the local currency. If you're in the middle of Europe you'll have a hard time finding a place that will just accept US dollars outside of some very tourist focused destinations. And even there I'm not sure if it'll work.

The places where I've seen this mostly work was near borders, and it makes sense that you'd accept the neighbour currency there even if it is some overhead. If you can quickly hop over the border you're much less likely to exchange currency before than if you plan a full trip in a different country.