It's not just soaps though. Lots of programmes have trigger warnings. Interestingly, many repeats of things that went out without comment in the 70s and 80s now have warnings about offensive content, which is usually unacceptable language.
As I remember it, swearing was less acceptable then than now, but racially insensitive language was standard, and attitudes to women were jaw-dropping. I saw a repeat of Auf Wedersehn Pet, which I remember loving back in the day, and was quite shocked. All of which suggests that it at least some of the warnings are maybe to pre-empt complaints - if there has been a warning you can choose not to watch if you are going to be upset by 'attitudes of the day', and the channels can argue that you did so with informed consent.
I don't know - are we becoming more sensitive? People like Mary Whitehouse used to argue that if TV continued to show things of which she disapproved we would all become savages, but the reverse seems to have happened.
Things you find stressful that other people don't notice.