Until I came to MN, I didn't know of mooncups/similar, I also didn't know that you shouldn't flush tampons.
Fine, I know now, but there will be loads of people who won't know because the information is simply not in people's faces. And when I started using san pro, the advice was to flush. I've not seen anything to update that since.
You go shopping and what you see is the scented disposable stuff. And the OP linked to one TV programme. I so rarely watch TV, and the kind of programme the OP linked would pass me by.
I now use a mooncup. And DD, aged 13, bags up her san pro and bins it, no flushing.