This really buries the lede. Telecoms are reluctant to do it because 'doing' it isn't aligned with their priorities.
Why would a telecom risk bankruptcy by investing heavily into a system that their competitors aren't?
If you want a back-door to exist (questionable) then the government either needs to have strong regulatory compliance where poor implementations receive a heavy fine such that telecoms who don't invest into a secure implementation get fined in excess of the investment cost or the government needs to fund the implementation itself.
