Imagine a trie implemented as a tree of dictionaries (ignore thinking about whether a tree of arrays may actually be better for now). Let’s say you want to implement an autocomplete algorithm based on a dictionary of words from a corpus. The autocomplete algorithm is naive: if a user types in “abc” you recommend whichever word starting in “abc” has the most occurrences in the corpus.

With ordered dicts you can use the trie to compute your autocomplete very quickly with no additional data structures. There are lots of other trie operations which are more efficient with ordered dicts too. I’m sure someone can come up with less complicated examples but this was the first one I thought of