Are these actually helpful to the site?
These tags are at best noise or at worse actively harmful.
This tag makes it easy for users to not think of tagging with [search], when really that's the topic we're interested in here. My understanding is that Search Server and Search Server Express are subsets of the mainstream SharePoint editions and don't give anything additional. Therefore, this tag should be made a synonym of [search] and our advice to the OP to mention the edition in the question (so answers aren't given for functionality not applicable to it).
Similarly would be better mentioned in the question not as a tag. There's nothing I'm aware of that's in this edition but not in SharePoint Standard. It just seems to be noise.
More generally, all it takes is for Microsoft to move functionality between SKUs and these tags are redundant anyway. Not using them helps to future-proof our content.
Tags work best when used for feature sets.
We should make the most of emphasizing this.