It's insecure by design because the NSA has for decades purposefully degraded the security of everything they can get their hands on to make it easier for them and law enforcement to spy on.
They don't want you listening in on John Q. Senator's phone calls, but they sure do...
The workaround is to carry around a small insulated faraday cage for your phone which blocks cellular reception, transmits bogus GPS signals locating yourself as a random wanderer, and plays television series reruns 24/7 at low volume into the microphone.
They don't want you listening in on John Q. Senator's phone calls, but they sure do...