You see, we've had government mandated "apps", but they are intentionally "hidden" (only by omission of course) from the layperson! So you, John Q. Public, are not exposed to them, but every regulated service provider is turned into a facilitator for law enforcement monitoring activity.
Bumping it down to handsets simply hasn't been done because it's just easier to plug in upstream through Third Party Doctrine and it'd be self-defeating in a sense to straight up make and admit that handsets purpose is to surveil you for law enforcement purposes. Businesses can have compliance compelled through the threat of disincorporation, so can be relied upon to cooperate as a pre-requisite of doing business.
Now, this software is generally considered "the good guys doing good guy things" so isn't generally considered problematic. As I hope is being learned by everyone; there is no line between a system that exists for well intentioned people to do good things with and a system capable of being used by evil people to do evil things, at scale with.
Look no further than CALEA mandated forensics packages on most network backbone gear!
https://www.subsentio.com/solutions/platforms-technologies/
https://www.fcc.gov/calea
You see, we've had government mandated "apps", but they are intentionally "hidden" (only by omission of course) from the layperson! So you, John Q. Public, are not exposed to them, but every regulated service provider is turned into a facilitator for law enforcement monitoring activity.
Bumping it down to handsets simply hasn't been done because it's just easier to plug in upstream through Third Party Doctrine and it'd be self-defeating in a sense to straight up make and admit that handsets purpose is to surveil you for law enforcement purposes. Businesses can have compliance compelled through the threat of disincorporation, so can be relied upon to cooperate as a pre-requisite of doing business.
Now, this software is generally considered "the good guys doing good guy things" so isn't generally considered problematic. As I hope is being learned by everyone; there is no line between a system that exists for well intentioned people to do good things with and a system capable of being used by evil people to do evil things, at scale with.