I noticed more and more bullion and coin sites accepting Bitcoin as payment. Got me wondering from a business point of view what are the tax implications for these businesses. I'm guessing they don't have to declare anything as they are sending bullion for Bitcoin and not money.
Depends.
Gambling sites can as well as porn sites too. A few days ago I noticed on some other sites too.
But not all sites declaring it. They just do it and customers pay without attention to that fact.