There's no such thing as technologically unable to comply.
If a nation state law enforcement insists, they will make you comply, and you and I will never hear about it.
A simple OS update with "If phone MAC == XXXXXXXXXX then send copy to FBI", targeted specifically at one phone, deployed only to that one phone, would go entirely unnoticed by the world.
And Official Secrets Act / equivalent, combined with a government-NDA and jail time for talking about it's very existence is literally routine. Has been since the days of black boxes in ISPs and them tapping Google's inter-datacentre links.
If someone like the FBI, NSA, MI5, GCHQ, etc. wants you to do something... you have literally zero choice in the matter. And talking about it will get you immediately jailed. And it really doesn't matter how big you are.
You think that Whatsapp end-to-end encryption is just going to make GCHQ etc. go "Oh well, nothing we can do?" No. If they need it, there'll be a guy knocking on your head office with a bunch of people, he'll only tell you why he's there in a closed meeting, you will comply, even if that means throwing everyone out of the datacentre and doing it yourself, and if anyone hears what he asked you to do, you will go to jail.
Been the same for decades. They just don't use it for ordinary crimes and petty stuff, mostly because of the resources they have to deploy to ensure that it stays quiet.