Maybe it’s worth having that security hole then. I think it’s a bit crazy that terrorists or child abusers can plan their crimes using WhatsApp without the police being able to intercept their messages.

Encryption exists. Terrorists and child abusers will use it whether WhatsApp or Apple or whoever implement it or not. Stopping those implementations is just denying privacy to regular users.

Also, if we’re able to contact our banks over the internet securely (and obviously the bank can still see everything about our accounts if they want, while criminals hopefully won’t be able to), then surely an equivalent should be possible for things like WhatsApp.

Law enforcement can’t eavesdrop on your encrypted connection to your bank. If they need to know about your banking activity, they rely on the bank reporting it to them.