If you're watching via iPlayer, then you also legally have to pay the license fee.

Fox would be tough since Disney technically doesn't own the Fox channel.

Legally, Disney can only own one of the major four basic channels. Hence since they own ABC, they couldn't acquire Fox itself. So Fox was spun out into a seperate company (along with Fox News and Fox Business) while Disney acquired all of Fox's original IP and such (like The Simpsons, Family Guy, etc).

I wouldn't be surprised if they offer live streaming of ABC via Hulu or something though.