Yeah and guess how good it works offline. You don't even know which country a place is in if you only know coordinates and have no access to the smartphone. Do a typo and there's no redundancy or error correction. You'll end up in some ocean then.
These attacks are valuable inputs for new generations, but no cause to consider 3G and 4G insecure in practice.
The authors learn about user's activity and location. But the comments often lack understanding what that means in context of mobile networks. Usually, it simply means:
* Is the user currently active in the cell?
If yes, the user's location is known (somewhere in this cell) and also his activity (he's online, otherwise he wouldn't be present). The authors here present an issue where the authentication procedure allows tracking with some probability.
The Internet was English speaking, western and had a keyboard with the Latin alphabet. These days are over, but it's injust to argue with ideology and a negative tone here.
The Internet serves people all-over the world and must respect local laws, because it serves the local people.
Also, free expression is stronger than ever before. You can now even claim your opinion is a fact.
To me, it's absolutely unclear what the author is actually talking about. Should telcos be responsible for monitoring the devices in their network?
Mobile networks provide Internet access with all the risks associated to the Internet. But the radio access is reasonably secure, if we compare with public WiFi. It's encrypted, authenticated and the operators are more trustworthy than the random person that puts up an Access-Point with years-old firmware. (the operators have something to loose here)
"use VPN" is a pretty strange advice if you consider how any shady providers there are. Switching you phone to 4G-only pretty much gives the same level of trust in the radio access.
Covering the webcam is just ridiculous. If someone has access to the webcam without obeying the standard interfaces in your browser and asking for permission, then the problem is not the webcam picture. Your computer is controlled by someone else.
Also I have trouble recommencing 2FA. User, password and e-mail access is considered one factor. Adding another one increases security over that - even if it's insecure SMS. But it often completely disables fallback authentication. The advice for 2FA should be: if you need 2FA, add a minimum of tree factors to allow recovery.