Indeed, this is not the case in the UK. Its too fucking expensive, and the paper work to approve that is too fucking hard. Most of the time the state will request search logs from google instead. its far cheaper and much higher signal to noise.
Also "intercept" evidence is inadmissible in court, so its not all that useful for convicting people.
Don't get me wrong, the UK like the USA has the ability to do all of this. But its used for specific actions (ie find a bomb-y needle in a haystack) where direct action is required.
AS I said, intercepted evidence won't convict someone here because it can't be used as evidence. so if they see that your messaging someone about planning some attrocity, you'll have to be caught in the act of planning, or a physical device with the messages have to be found.