Yes there is, for example Bristol, England - they do have their own currency which is accepted in many shops. Another city, Hull, was going to run their own cryptocurrency but I don't know how successful they are. Some cities popular with tourists also run their own currencies e.g. Polish Łeba.
Interesting article: Local UK currencies
Hmm. That is actually something interesting and I have not actually gotten to hear something like that before and apparently with this kind of thing, that is because it was generally accepted by the people within one specific niche if I may say just like you mentioned with the tourists in popular cities. Nonetheless, i feel it is still something that would not really fly that much. Interesting article: Local UK currencies
In that case, you should imagine the number of currencies that would actually be available in a single country and if you have to travel globally, how do you think people will be able to relate with themselves to even know what you are holding is a thing worth some value?
Have you been to altcoin exchange lately?
There could be some universal currency like bitcoin... maybe bitcoin itself.
Also, these local currencies are created by locals and for locals to avoid e.g. unfair rules associated with government printed money. I don't think they care that much about global acceptance.