Same goes for phones (and by extention, fax). Since wire tapping is already illegal, it doesn't need to be secure (at least going by the law).

I agree the laws need an update. I'd imagine a general 'common communication channels' or whatever would work, rather than specifing every single one that's allowed to be used. That way, it's still illegal to snoop on your communications, regardless of whether they happen by post, phone, email, SMS, Whatsapp, or whatever else we end up using in 20 years.