That is because most of the tag editor edits ID3 tags of songs. TagMusic directly makes changes to Android Mediastore. It is a database where android stores metadata of songs.
Benefits of tagging Mediastore are:
* No need to reboot the phone to update tags.
* No need for scanning media.
* Albums with same name will be merged automatically.
* Songs with same artist will be merged automatically.
* Updates tags almost instantaneously.
* Move a song to an existing album.
* Delete songs (support for Kitkat)
* Edit song title, artist, album, year, track, genre, composer and disc number of songs.
* Edit album and artist of albums.
* Insert or update cover art of albums
* Delete album (without deleting songs).
TagMusic Lite apk size will always be less than 2 Mb.