Agreed. I don't see how any "count" can be completely accurate. In England, a few places with cathedrals don't, strictly speaking, rank as cities - for example, Bury St.Edmunds in Suffolk.
Moreover, what of places in North Germany that have a "Dom" (often translated as "cathedral") that isn't a diocesan see - for example, Bremen, where the local "territorial church" ("Landeskirche") is Reformed and doesn't have bishops. The complications are simply endless.