We don't document in http://www.unicode.org/reports/tr35/ that the count= attributes have special aliasing. They act as if there were root aliases for all of them.
In particular, if there is no value for a path, and it has a [@count="x"] attribute and value, then:
If "x" is anything but "other", it maps to [@count="other"]
So //ldml/foo[@count="one"] would map to //ldml/foo[@count="other"].
2. In the special case of currencies, if the count="other" value is missing, it maps to the path that is completely missing the count item.
So //ldml/foo[@count="other"] would map to //ldml/foo.
We hadn't added all those aliases to root because it would be a huge number (and growing, as we add units). Note: it would be possible to generalize #2 to all cases, because it would only apply to currencies.