In my purely anecdotal experience, town used to be a whole lot worse in the 70s and 80s than it is now. Again, no consolation to those who have run into trouble through no fault of their own whilst in town in recent times, though.
I couldn´t comment on town specifically in the 70s and 80s, but to add to your anecdotal experience there is plenty of cold hard data that shows Britain was a far more violent place right across the board in the 80s (harder to find data from the 70s) - and it is only makes sense that this seeped into town.
https://www.ons.gov.uk/peoplepopulationandcommunity/crimeandjustice/bulletins/crimeinenglandandwales/yearendingseptember2019Number of violent crimes in 1981 : 2,063,000
Number of violent crimes in 1995 : 4,465,000 (Peak)
Number of violent crimes in 2019 : 1,285,000
Number of murders in 2003 : 1,047
Number of murders in 2019 : 617
What unfortunately does seem to have risen over the last decade (harder to find data for 70s and 80s) is gun and knife crime.
I think you are probably spot on that perceptions of crime are enhanced by the 24/7 news cycle. More locally the fact our only source of local news is an absolute gutter rag that revels in crime stories doesn´t help.
All that said I have definitely seem some crazy stuff in Liverpool in my time, and/or know of it. And if you do live in areas where a lot of crimes do happen or are on the increase, of course you are going to come out with a different opinion as ultimately lived experience trumps statistics if you are on the recieving end.