There is an automatic job that deletes single-use tags after 6 months. No attempt is made at determining whether the tags are good and should remain, or whether the tags are a variant name of another tag and should be renamed or made synonyms. Even beta sites, where it is expected that the tag system is still evolving, are not exempt. This job is not subject to any review, not even after the fact: one day the tags are there, the next day they're gone.
There is one way to prevent a tag from automatic deletion: write a tag wiki (which is a good idea anyway).
Given that a lot of tags on Travel are the names of locations which anyone looking for information would use, it doesn't make sense to remove them. Experience shows that users are already hunting down low-use tags, the automatic job is at most a minor help — and it does harm when it removes good tags. (How many useful tags have thus disappeared? There's no way to know.)
- turn off the job that deletes single-use tag, and provide a log of past deleted tags so that we can add them back where appropriate; or
- provide evidence that the deletions were beneficial to the site (I don't know what form the evidence could take other than a log of past deleted tags so that we can ascertain that the tags were indeed useless in a vast majority of cases).