I just went thru my receipts and they aren't charging tax on ebooks either. I swear I did get charged once a few years ago. I don't have any for movies/tv shows though, so I can't check them. Well I might, but they'd be old.
The law (which i haven't read/clicked on yet) could be written to not include electronically downloaded material. I would imagine that whatever the reason is it isn't done, it won't be "too long" before it happens. Which is going to muck up using iTunes cards... Because then you have to think about tax and mention that the kids!
Eta:
that is from the iTunes store terms and conditions.... So obviously FL hasn't done this. Yet.
http://www.apple.com/legal/itunes/us/terms.html#GIFTS