> [...] The lazy option for a police agency would just be to purchase or develop a couple mobile browser exploits, and then serve warrants to French telcos requiring them to MitM targeted traffic. [...]

This seems highly unlikely to not alert someone as the camera / video / GPS icons would show up as being in use.

> Most people also seem to be overlooking the low-tech solution - get a warrant to break into the target's house or seize their phone during a "random" traffic stop, and use physical access to the device to do whatever.

I think people are not really overlooking, but the question is related to the remote enabling of GPS / Video / Audio interception. This kinda excludes random traffic stops or breaking into someone's house.

As such, "do significant vulnerability research on closed source hardware/software to find vulnerabilities across common baseband processors" seems like a way to achieve this.