SMS rates are absolutely bonkers considering the technical way they're transmitted. The US is an outlier in SMS rates actually being reasonable (usually unlimited or close to) for consumers - but for the rest of the world the insane mark up on that communication method has mostly obsoleted it...
That'd be all well and good... the technology would die naturally, but all my American relatives continue to stubbornly use iMessage.
Signal pays more for delivering verification SMS during sign-up, than for all other infrastructure (except traffic) combined. Wow, that sounds excessive.