I ran across the first ID3v2.2 tag I've seen, yesterday. This version was created in '98, and is considered obsolete. The more recent ID3v2.3 (also '98) is the most common version.
For some unknown reason, iTunes, according to Wikipedia (and other sources) "writes tags in Unicode ID3v2.2 by default." iTunes was released in 2001.
I can't think of a good reason for Apple to use it in the first place, and I can't think of a good reason for them to keep using it.