I.e. cash, rural, paper letters for last mile
The internet is by definition centralized and the government has privileged access, from a surveillance perspective. Luckily, the number of people who really need this level of anonymity (i.e. I am wanted by every world government as a top priority) is pretty low.
I think this is the only way to feel truly at ease with the state of things, really. Keeping a whole self in public or in private is asking a bit much.
You have layers and layers of technology in even the simplest modern computers, and core network infrastructure subject to tapping or worse.
And much of this that can be done from anywhere on the planet.
Analog requires physical proximity, a strength and a serious inconvenience. But it also has the property of being legacy, in that you are now immune to state of the art digital methods, and susceptible to older ones that may be out of institutional memory and practice.
**SPOILERS** Once the US that's basically our world discovers the existence of "world walkers" when they nuke the Whitehouse, it quickly steps into an authoritarian surveillance hellstate capable of realtime surveiling the population around the country to the point where they can track people entering their timeline because they were on camera exiting a building they were never recorded entering, or were flagged buying a plane/bus ticket from a city they shouldn't have been in according to previous records, or in one case for leaving a coffee shop with a noticeably empty backpack when she'd entered the shop with it completely full, having passed the contents to a world walker she was meeting. That irregularity automatically flagged everyone entering/leaving that building for review in their system and they backtracked all of these people through their paths that day until finding the gap where he'd stepped through to their world. That all happened in a matter of minutes and then quickly homed in on him.
Anyhow,it goes into detail about the lengths they go to to avoid detection by these systems and honestly didn't strike me at as all farfetched. The technology and capacity exists and it's a concentrated effort on part of the government is all it would take to implement it.
The surveillance state is already here. The dragnet is on for everyone, and if they miss anything it's because it's hidden in the noise, not that the signal isn't being sent.
We're cooked, it's over. Forget being anonymous.