There's a lot to be said for the protection that real world impediments
can introduce to even the most sophisticated all-electronic methods.
Take networks. You have firewalls, multiple tiers of authentication, encryption, etc. But if you absolutely want to be 100% sure you keep things out, the single best "solution" is to send a junior tech down to the wire room and have them physically pull the cable from the WAN port(s) on your router(s).
And yeah, that's one reason why it's almost always uniquely color coded. You'll find a single yellow or red cable in almost every network switch room. Two guesses what it is.
Last I heard, one time cipher pads and 'spy' paper are still among the most bulletproof and secure of all covert communications methodologies. So it hardly surprises me typewriters are making a limited comeback. No tool like an old tool...