Scientists do in fact report how confident they are in their findings. Read original sources, most of them say things like "in X% of observed cases there was a Y% of Z over the course of T with confidence level of P".
But that sells a lot less clicks than "SCIENCE SAYS LOW SALT IS BAD FOR YOU OMG"
The truth of the matter is that the general public shouldn't be reading scientific publications, because without the context of the intended audience, reasoning about what you read is incredibly difficult or impossible. This is doubly true for 'science journalists' who so very rarely are educated to be able to correctly translate and very often distill a paper into an incorrect and baiting article with only the tiniest shreds of truth.
The confidence rating you mention has little value to the general public, and even among scientists, the value of 'p-value' is questionable and the matter of occasional debate.
But that sells a lot less clicks than "SCIENCE SAYS LOW SALT IS BAD FOR YOU OMG"