Some tags have a very low use level, and therefore practically no-one has the score to vote on synonyms for it. For example, the SO image-resizing tag. There is a synonym in the queue: image-resize. Because it's such a low-use tag, almost no-one can vote on it.
- Vary the score required to vote by how much the tag is used
- Allow users with enough score in related tags to vote
- Allow Trusted Users (20k) to create synonyms regardless of usage