If you want cookies to be global, set them to / or leave out the path. If you want more fine-grained cookies, use a specific path. What's the problem? Currency is—in your example—clearly a site-wide setting. I think sites should make more of their hierarchical structure, not less.
If you leave out the path, it will default to the directory of the current URL, not /.
If not for this default behavior, it would have been much easier to manage global settings such as currency. Right now, all it takes is one cookie without a path to introduce inconsistency, only on some pages, in a way that's hard to reproduce.
