Earlier quoted context omitted.
That wasn't the case in the past. Events over the past 15 years have resulted in most companies encrypting all traffic between datacenters (due to the perceived risk). TLS between consumers and companies is probably at an all time high though due to a push for end-to-end encryption.
TLS doesn't help here, because state actors (including China, Russia) own trusted root certificates, which allow them to TLS-terminate for _any_ website they choose and silently decrypt/MITM the traffic.
And eavesdrop is one thing but I'm not clear how you could MITM an undersea cable without the operators noticing.