I have no idea why some cases attract more attention than others. Although it is notable that the case of Sarah Everard only reached real fever pitch after it was revealed a police officer had been arrested.
There are around 176,000 people go missing every year. I find that staggering. The vast majority do turn up, but even so, there are those never heard of again. And so many are not reported in the press.
I do remember the murders in Ipswich in 2006 and when the first young lady went missing it was only locally that it was really known. Even after a second girl went missing there was no real national news coverage. It was only when a body was found and other ladies disappeared that it really got attention. Then the press descended.
It is, sadly, a feature of my work that I have to deal with missing persons since often they have property that needs dealing with. Not one of the many cases I have dealt with has had real national coverage. There are in fact other murders and attempted murders that do not ever seem to be reported.
I just did a quick search and was quite shocked at the table I found that states for the year ending March 2020, there were 695 murders. (Data here:-
https://www.ons.gov.uk/peoplepopulationandcommunity/crimeandjustice/articles/homicideinenglandandwales/yearendingmarch2020). I certainly do not recall seeing nearly 2 murders reported every day.
I wonder though whether the reason is that her death was at the hands of a stranger. Very often murder occurs between people known to each other. Horrific as that is, there is often some motive such as adultery, money or jealousy. A murder by a stranger is in some ways more chilling since there is generally no other motive than sexual or primeval gratification or instant uncontrolled anger.