I don't have first hand experience of any issues at Chester, or anywhere else for that matter, just second hand, so perhaps a pinch of salt in order. I also suspect that CCTV operators generally recognise other signs like not having a bag or crying or looking a bit spaced out etc etc to determine whether somebody may be at risk (of suicide, or even a drugs or medical episode).
Tesco, Sainsbury's, Lidl, Aldi, Morrisons all have this at some location. It's not very widespread, but is becoming more common in certain parts of London.
Wholesalers like Costco have had it for a while.
I've even heard that some non-grocery retailers like IKEA and Primark have it in places, but I've never seen that myself.
I just choose not to shop at these places. Maybe it'll become the norm at some point and I'll have to succumb to it, but I'm don't really like the experience so I stopped using those Tesco Express shops near my old work in London.