Movies and TV Beta why are important tags for famous franchises like saw not there?
I even think that
Movies and TV Beta doesn't have many tags.
Tags are created by Moderators and users who have enough rep to do so
That being said, tags are deleted after a week of having no questions attached to them. Also, the only way to create tags is to place them on a question when one has enough rep to do so.
From this you can see that it is actually impossible to have tags for franchises that have no questions, despite their apparent popularity, because it is impossible to have tags for questions that don't exist.
For being in beta for only about 5 months, we have about 540 tags, which is no small number, but it will definitely take time to increase this number to actual graduated site level.
If you find that a tag is not created for a question and you do not have the rep to do so, leave a note in the question and a Mod or someone with enough rep to edit tags will clean it up for you.