This is only because of the design defect that "lawful intercept" requires.
Telecoms should be completely untrusted because everything is end-to-end encrypted. Compromising a telecom shouldn't allow you to do anything other than bring about a denial of service, and even that would only be effective against anyone who didn't have a redundant link with a different provider, which all actually critical infrastructure should. And a denial of service is conspicuous, as opposed to spying on required-to-be-unencrypted traffic which can continue undetected indefinitely and is a significant national security risk.
Our need to not be spied on is greater than our need to spy on ourselves and requiring designs that assume the opposite of that is a major self-imposed security vulnerability.